Historical Review of Cruiser Characteristics, Roles and Missions

SFAC Report Number 9030-04-C1

Sims, Philip; Bosworth, Michael; Cable, Chris; Fireman, Howard. Authors' signature page

Report Documentation Page - in Adobe pdf format

ABSTRACT

The purpose of this study was to survey the historical roles and mission of ships called "cruisers" in preparation for a Navy study of future class of cruisers. The current generation of ships of that name are assigned an aircraft carrier escort mission and are specifically optimized for that role. However, the first role assigned to cruisers was as foreign station ships, independently deployed, looking out for national interests around the world. Other cruisers has been designed as sea denial ships, as counter-raider merchant ship escorts, as a substitutes for battleships in a battleline, command ships, and as reconnaissance platforms (either directly or via launched smaller vehicles). There have been several proposals for cruiser-aircraft carriers hybrids and one Japanese class was constructed to that concept.

EXECUTIVE SUMMARY

"What is a cruiser?" With the VLS versions of the CG 47 class in routine service, it would seem the answer is self-evident. However, the CG 47 class is a recent specialized cruiser variant which is optimized as a large aircraft carrier AAW/ASW escort. That role drove the designers towards a high speed, lightly or unarmored ship that is expected to receive supplies (hence, have limited endurance) as component of a deployed carrier battle group. The Navy needs to examine the assumption that a one-for-one replacement for those ships (focused on the carrier escort role) is needed. Due to large number of DDG 51 class ships, which are also carrier escort capable, it may be desirable to focus a future cruiser on different missions. This study surveys the historical roles of ships called "cruisers" to develop a list of possible missions for a future cruiser. If a future cruiser takes on some of the many other roles performed by cruisers in the past, it might be a much different design than the CG 47.

The historical survey shows that ships with the name "cruiser" have covered these missions:

• Foreign station ships, independently deployed, looked out for national interests around the world. In addition to an extensive gun armament, the station ship had self-repair capability, long range, and "first-responder-to-disorder" equipment such as small arms for the crew and an extensive boat outfit. The disorder could be a revolutionary situation or a natural disaster.

• Sea denial ships, using their pre-deployed location, attacked other nations' trade routes. Counter-raider merchant ship escorts would, in turn, try to stop enemy sea denial ships.

• The Washington Battleship construction limitation treaties made large cruisers into substitutes for battleships in an alternative battle line (especially for night time combat). The attempt to forge a homogenous cruiser battle line ended up making US and Japanese "light" cruisers the same size and weight as "heavy" cruisers. The French and Italian navies specialized in "interceptor" cruisers –

• sacrificing many other ship features, such as range, for speed and armament. The Soviet Union's first cruisers were based on Italian designs which explains their heavy armament on smaller displacements.
• Cruisers have served as command ships at many levels, from small group leader to provisions for carrying the national command authority.

• Cruisers have served as reconnaissance platforms (either directly as fast scout cruisers or via launching and retrieving smaller vehicles such as float planes).

• The "C" in CV reflects the fact some of the first aircraft carriers were armed with cruiser caliber guns for self-protection and thus thought of as part of the cruiser family. The CVs lost their gun armament in favor of more aircraft but depended on gun cruiser protection (prior to all weather/day/night aircraft) when night/fog/bad weather left a carrier helpless against enemy surface combatants.

• Smaller cruisers (CLAA) took on the role of gun armed AAW specialists able to keep up with the carriers regardless of sea conditions.

• There have been several proposals for cruiser-aircraft carrier hybrids and one Japanese cruiser class was constructed to a float plane version of that concept.

• There have been a few highly specialized variants such as cruiser minelayers and dedicated training cruisers.

• Cruisers served as anti-battleship (UK WWII) and anti-carrier (USSR 1950-60s) deep ocean barrier picket ships and, once a target had been identified, as high-speed long-distance tattletales.

• Cruisers supplied amphibious gunfire support to land forces at the start of wars until the more operationally expensive battleships could be reactivated.

• Currently USN CGs and CGNs serve as aircraft carrier escorts providing AAW and ASW.

• Independent land strike capability became a cruiser feature with the fitting of Tomahawk to the CG 52 onward.

A summary of the changing mission assigned to ship designated as cruisers follows.

It appears that the consistent theme of all the traditional missions was a ship with long endurance and the potential for independent operations. Sometimes this theme was strongly emphasized as in ships for the foreign station, commerce raider and commerce defender roles. Sometime those characteristics dwindled in ship customized for specialist roles such as the battle fleet scout cruiser of WWI, the cruiser minelayers and the highly optimized big carrier escorts of the US of the last half of the 20th century.

If a future cruiser is not a dedicated AAW/ASW carrier escort (intended to surge with the carrier battle groups), it may pick up modern versions of some of the historical roles:

• A forward deployed "Sea Swap" unit, with the carrier battle groups based in the United States instead on constant patrol, would return the cruiser to the independent station ship role.

• Future cruisers will not serve as sea denial raiders in declared wars because submarines are so much better at it. However, a modern sea denial role is intercepting and searching merchant ships in remote ocean locations to see if they are transporting terrorists or serving as Trojan horses for destructive weapons to be delivered to a US port.

• Future cruisers will not conduct anti-surface raider barrier patrols, but could provide a ballistic missile defense barrier, the modern equivalent. This role requires a ship with the traditional cruiser virtues of endless boring patrolling (reliability, seakeeping, crew comfort) with the possibility of sudden unanticipated action (100% availability, time critical response, independent action).

• Future cruisers will not carry float planes, but they may be a launch/recovery platform for the modern analog of unmanned vehicles (air, surface or underwater).

A return to other missions will, in turn, cause ship designers to put modern versions of other hull features, found in the previous cruisers types, into a new ship:

• Increased survivability, especially against ambush attacks, including a return to structural armor,

• Increased stores and fuel loads for independent operations,

• Increased self repair stores and shops to allow staying on station for extended period while remaining fully capable,

• First responder capabilities (such as limited medical facilities, small arms for the crew and an extensive boat/helo outfit), and

• Crew sized not only to operate the ship but to put small detachments ashore or on seized merchant ships.

• Provisions for carrying a small command staff and a senior officer (if assigned a role in the command structure).

The hull features listed above noticeably increase ship size (dimension and weight) compared to the current generation of lightly-protected aluminum superstructure ships bearing the cruiser name. However, most of those features have relatively low construction costs and a relatively small life cycle cost impact. Note that the associated higher manning level for self-repair, first responder role and detachment operations would carry a noticeable life cycle penalty. A combined nuclear cruiser with gas turbine boost (CONAG) plant would increase initial cost and crew cost but, at the fleet level, might pay off by reducing the logistic train required to support a ship assigned to a remote station for long periods of time or eliminate the vulnerability caused by using regional port facilities.

TABLE OF CONTENTS

• Introduction
• The Wooden Sailing Ships
• Cruiser Development 1890's to WWI Era
  • Early Developments
  • Shift from armored to unarmored
  • Communications
• Cruiser Development 1920-1938
  • US Navy leading up to the Washington Naval Treaty
    • Omaha Class
    • Pre-1922 Heavy Cruisers
    • Pre-1922 Battle Cruisers
  • Washington Naval Treaty
  • 1st Generation Treaty Cruisers
    • Foreign Activity
    • Pensacola Class
    • Northampton Class
    • The "Treaty Tinclads": Pensacola and Northampton Classes
  • 2nd Generation Treaty Cruisers
    • Portland Class
    • New Orleans Class
  • Geneva Summit and the London Naval Treaty of 1930
    • Flying-Deck Cruisers
    • Erie Class Gunboats
    • Brooklyn Class Light Cruisers
    • USS Wichita
  • The End of the Treaty Limited Cruisers
  • Inter-War U.S. Fleet Organization and Cruiser Employment
• Cruiser Development WWII
  • Foreign threats
  • Wartime roles and missions
  • Wartime Design Evolution and Building Program
  • New US Wartime Designs
• Cruiser Development Post WWII to Early 1960's
  • Post WWII Political Environment and Fleet Employment
  • Surface Warfare and Shore Bombardment Missions
    • Culmination of the Heavy Cruiser's Evolution: Des Moines Class
  • Task Force Air Defense Mission
    • The Antiaircraft Cruiser
    • Missile developments
    • Electronics
    • Missile Cruiser Conversions
    • DLG evolution
  • Antisubmarine Warfare Mission
    • The Hunter-Killer Cruiser Norfolk (CLK 1)
  • Command Cruiser Mission
    • CA/CLG/CG Fleet Flagships
    • Command Cruisers
  • Parallel British Developments
• Cruiser Development Mid 1960's to Early 1980's
  • US Missile Cruiser Designs
    • CGN 9 Long Beach
    • Leahy (DLG 16) Class
    • Belknap (DLG 26) Class
    • Bainbridge (CGN 25)
    • Truxtun (CGN 35)
    • California Class (CGN 36, ex-DLGN 36)
    • Virginia (CGN 38) Class
    • Vietnam Employment
    • DLG Redesignation to CG
    • Major In-Service Upgrades
  • Aviation Capability Evolution
    • DASH to LAMPS
    • NATO Aviation Capable Cruisers
  • Soviet Union Developments
    • Pre-1960 Developments
    • 1960's & early 70's Developments
    • Final Soviet Cruiser Developments
• Cruiser Development: Aegis Era and Beyond
  • The Aegis Era
  • The DDG 51 and Alternative Modern CG Studies
  • Beyond the CG 47
• Conclusions

LIST OF TABLES

Table 1 A Description of a Royal Navy cruiser
Table 2 Royal Navy Destroyer vs Cruiser Practice in 1957
Table 3 Changing Roles of Cruisers

LIST OF FIGURES

Figure 1 C10 Concord..... 13
Figure 2 Battle Cruiser HMS Hood..... 15
Figure 3 CA24 Pensacola ..... 23
Figure 4 CA 29 Chicago ..... 25
Figure 5 CA 35 Indianapolis ..... 27
Figure 6 CA 38 San Francisco ..... 28
Figure 7 Immune Zone..... 32
Figure 8 CL 43 Nashville ..... 36
Figure 9 CA45 Wichita ..... 38
Figure 10 USS Augusta Observing Sino-Japanese Fighting ..... 40
Figure 11 Japanese Heavy Cruiser Haguro (Myoko Class)..... 43
Figure 12 German Light Cruiser Köln (Königsberg Class)..... 44
Figure 13 SOC Seagull in Cruiser Hangar..... 48
Figure 14 USS Terror (CM 5)..... 53
Figure 15 HMS Dido Antiaircraft Cruiser..... 54
Figure 16 USS Atlanta Antiaircraft Cruiser. ..... 55
Figure 17 USS Worcester Antiaircraft Cruiser ..... 62
Figure 18 USS Columbus as CA 74 (top) and After Conversion to CG 12..... 66
Figure 19 Flag vs. Non-flag Configured CLG's..... 70
Figure 20 USS Dale (DLG 19)..... 78
Figure 21 All Nuclear Task Group including USS Bainbridge (DLGN 25) (top) and USS Long Beach CGN 9) (middle)..... 84
Figure 22 Belknap Class USS Fox (CG 33) after installation of Harpoon and CIWS. ..... 93
Figure 23 HMS Invincible...... 96
Figure 24 USS Norton Sound fitted with AEGIS System ..... 101
Figure 25 CG 62 USS Chancellorsville..... 105
Figure 26 CGBL; a CG 47 combat system but with the hull features of a DDG 51, weapons systems modularity and increased service life reserves..... 107
Figure 27 A painting of a hybrid Aegis cruiser and light carrier ship: the Mission Essential Unit ..... 108
Figure 28 Artist Concept: CG(X) and SC-21 Family..... 109
Figure 29 Displacement Trends ..... 112

ACKNOWLEDGEMENTS

The contributions of the co-authors, Steven Toby of JJMA, William Garzke and Douglas Harrison of CSC and Jonathan Applequist, Thomas Schubert and Robert Scott of Gibbs and Cox are gratefully acknowledged.

Sean Walsh JJMA Lead Author

LIST OF ACRONYMS

1. INTRODUCTION

Ships called "cruisers" have been part of world navies for over 150 years. Because of their long history everyone involved with the United States Navy (USN) has at least a general understanding of the ship type. However, while there is widespread agreement among naval planners that the USN should have a new cruiser (CG(X)) to replace the existing Ticonderoga class (CG 47) when they go out of service in 15-20 years, it is not clear exactly what they have in mind. Is it the independent operations cruiser of the first half of the 20th century? Is it a specialized large carrier escort characteristic of most USN cruisers of the last half of the 20th century? Is it a sea-denial-to-the-enemy asset or a distant lanes-of-communications guardian? Is it a "Sea Swap" first responder to a crisis which serves to contain it while awaiting the deployment of the major "Surge" battle groups?

Even the basic cruiser nomenclature is confusing. What is a 'protected' vice 'armored' vice 'scout' vice 'battle' cruiser? Why is a 1930's 'light cruiser' the same size and displacement as a 'heavy' cruiser? Why were some cruisers as large as, or even larger than, the equivalent era battleships? Why did ships that USN had long classified as big destroyers (DLs, DLGNs, DDG 47s) become cruisers overnight?

The purpose of this paper is to explore the history of the cruisers, looking at their performance characteristics, the roles they were formally assigned in force planning, and the actual missions that they were pressed into during wars and other emergencies. From this will be derived a checklist of potential cruiser roles to serve as a means of surveying naval planners "is this what you mean when you say 'cruiser'?". If there is agreement that any future CG is a direct continuation of the CG 52-73 carrier escort (plus land attack missile role) product line, that will greatly simplify the amount of work in an Analysis of Alternatives (AoA). However, if use of the checklist shows a wide divergence in thought about other cruiser roles, then the AoA work will greatly expand and possibly result in recommending not just one CG but a family of ships to take on the various, sometimes incompatible, cruiser roles.

2. THE WOODEN SAILING SHIPS

The word "cruiser" was first used in English in 1651. It was derived from related terms in Dutch, Portuguese, and French, all of which had the meaning of "crossing", as in crossing back and forth across the entrance to a harbor to enforce a blockade, or crossing an ocean. In 1694, British Parliament documents indicate that 5th and 6th rate ships were detached from main fleets to "cruise" to protect merchant shipping. Documents of this period also mention independent "cruising" in search of enemy vessels.

The suitability of a wooden sailing frigate to fill this role stemmed from its speed, one continuous gun deck, plus berth deck design features, and increased stores capacity [Appendix A]. It was suitable for long range operations in remote areas where crew comfort, self-reliance, seaworthiness, and endurance were important. The frigate's speed advantage made it useful for scouting and reconnaissance, as well as facilitating the long voyages for which its increased stores capacity per man also made it suitable.

Sailing frigates also had a role in fleet operations. While their lighter scantlings made them too vulnerable to take a position in the column of capital ships, they could maneuver on the disengaged side of the line to transmit signals, or on the engaged side at a safe distance from the enemy to report his movements. Because they had nearly the same sail power as a ship of the line, they could take a crippled capital ship under tow to disengage it from the battle, or rescue the crew of a sinking ship. As a result of the loss of the French flagship at the Battle of the Saintes (1782), it became common for admirals to choose frigates as flagships so that, not being a primary target of the enemy's ships of the line, they could still maintain control of the battle.

The commanding officer of a frigate was always a full Captain in the British Navy, a "post Captain", since during independent operations or as senior-officer-onstation in remote areas, important decisions about employing force would have to be made without directions from the Admiralty.

3. CRUISER DEVELOPMENT 1890'S TO WWI ERA

3.1 Early Developments

The cruiser as a named ship type evolved when the world's navies phased out sail propulsion and wooden hulls, creating the armored, steel battleship to replace the sailing ship of the line as the means of enforcing or seizing command of the sea in a fleet action. Early battleships were big - the largest warships in history when introduced rather slow, and had relatively short endurance even when aided by auxiliary sail. These characteristics opened up a niche for various types of smaller warships. The cruiser was created to fill several of these niches.

Very small ships were created at the same time for the sea denial mission. Using newly developed underwater weapons such as mines and torpedoes, these ships could sink the largest ships and prevent a dominant power from taking advantage of control of the sea even after it had been achieved. These very small ships, torpedo boats and submarines, had extremely limited range and even less seaworthiness. Therefore, they were only helpful in what would today be called littoral warfare – breaking a blockade or countering a shore bombardment operation. They were not capable of intercepting an enemy's merchant ships or fleet on the high seas.

With the emergence of a naval strategy using large battleships and small torpedo boats and submarines, the need arose for the functions of a middle-sized combatant, later to be called the cruiser. One of these functions was that of a commerce raider, which had to have global range, and enough speed to outrun the fastest merchant ship or battleship. The commerce raider must also have enough capacity to house the crews of the captured or sunk merchant ships; in those days it would be considered unacceptable to leave them in their lifeboats. Prize crews might also be required for ships carrying exceptionally valuable cargoes.

Another cruiser mission was to "show the flag" on a foreign station. While this would seem to be a mainly ceremonial function, in those days the "station ship" might also be required to take action to protect the interests of its nationals when their rights or property were infringed upon by irate locals in what would now be called the Third World, with or without approval from the local government. This "gunboat" mission would not be suitable for a ship as big and expensive as a battleship, and required somewhat different naval architecture than the commerce raider mission (speed had almost no value, for instance). Nevertheless a mid-size vessel was still required to carry the naval representative (often a flag officer) and his staff, a Marine detachment, and sufficient personnel and equipment to do most of their own maintenance in remote, primitive areas not equipped to service mechanized hardware. An elegantly fitted-out wardroom and well-equipped galley was another requirement, since the gunboat was required to do substantial entertaining, of ambassadors and local dignitaries. A full complement of boats was often needed to ferry the guests ashore if the ship had to anchor out for security or other operational reasons. Depending on the level of threat on the foreign station or on how badly the diplomats handled foreign relations, the "gunboat" mission could escalate into a power projection operation, where the station ship would have to perform battleship-like functions of shore bombardment and sea control. Evidently, this could quickly lead to a much more capable ship being called for, and actually sending a battleship might not be possible due to considerations of maintaining the "fleet in being."

The sea-denial functions of both cruisers and the small warships mentioned earlier called for a "counter-sea denial" function. A mid-size warship was needed to escort merchant ships to drive off commerce-raiding cruisers and pirates, as well as to escort battleships to guard them against torpedo boats and submarines (and later destroyers). These missions, like the commerce raider mission, called for substantial speed and seaworthiness so that the cruiser could keep station on the ship being escorted in all weathers, even if it could not necessarily match the speed of the sea denial vessel. A cruiser need not overhaul such a craft in a stern chase; it just had to force it away from the ship being escorted without the cruiser itself being too easy a target.

Finally, in an age before spy satellites or airborne reconnaissance, cruisers had a scouting function. The "scout cruiser" was a smaller vessel of extreme speed whose other main attribute was tall masts to hold up the spotters' tops and later the radio antennas with which the ship could report what it had seen. It needed to be able to defend itself against lesser ships long enough that its report could get through to the force commander, so if we imagine this function as integrated with the fleet or helping the battleships to find their targets, a scout cruiser might not necessarily be small. On the other hand, scouting could also be more like espionage, and for that function a small and less belligerent-looking ship would be more suitable. "Strategic scouting", providing advance warning of the departure of an enemy fleet from its base, might also call for a large number of units to provide sufficient coverage to shadow the enemy. This would again lead to many smaller, less expensive units, which still needed high speed capability.

Accordingly, ship designers developed cruisers as mid-size combatants to do these principal missions. Different navies stressed some missions more than others, and most navies built cruisers in different sizes and configurations to suit the mission their doctrine put at the top of their priority list. For example, British designers stressed the counter-sea denial and station ship/gunboat mission, while French and German designers preferred sea denial. This was a natural consequence of the dominant position of the British Navy in the Victorian period and the second-rate character of the smaller European navies.

The United States entered the cruiser market late, without extensive experience of iron and steel ship construction. But, our designers seem to have studied the activity of the foreign navies, especially the British, and even our earliest cruisers, dating to around 1890, showed the influence of European experience.

From the beginning of steel navies, it was recognized that simply scaling down all functions uniformly from a capital ship would not produce a satisfactory cruiser. Such a ship would have guns that couldn"t penetrate battleship armor and armor that couldn"t protect against battleship gunfire; she would be slower than a battleship because of the disadvantage of a shorter waterline, and would still lack an advantage in range. Therefore, such a ship would be hopelessly outclassed by hostile battleships and unable to keep in range of commerce raiding cruisers long enough to damage them. Such a ship would be more heavily armed than required for the station ship or scouting roles and more heavily armored than required against guns less potent than those mounted on battleships or shore batteries.

However, in the power projection or high threat gunboat role, it was apparent that the cruiser was a cheaper and less capable stand-in for a battleship. This was the origin of the first class or "armored cruiser," a larger ship with substantial armor over most of its vital areas that was thinner than battleship armor, a scaled-down battleship-type armament, but an extra dose of speed and endurance so that it could theoretically run away from an encounter with a battleship. From this description, it is implicit that the armored cruiser would not necessarily be smaller than a contemporary battleship, since speed and fuel capacity lead to increased ship size. Armored cruisers varied substantially in size; our largest, the "Big Ten" of 1905-6, were over 15,000 tons and longer than contemporary battleships, which generally displaced less than 18,000. They were named after states in a further demonstration of their near-capital ship status. The Maine, whose destruction in Havana Harbor triggered the Spanish-American War, was designed as an armored cruiser (to a modified British design) but later redesignated a second class battleship; she was both smaller and slower than the contemporary armored cruiser New York, but carried heavier main armament.

Moving down the size scale, a "second class" or "protected cruiser" had less armor and was generally smaller than an armored cruiser. In most sources protected cruisers are described as having an armored protective deck but no waterline belt; US protected cruisers mostly followed this scheme, but one class had a 4-inch belt and all had additional armor around weapons and conning tower. Protected cruisers were usually faster than armored cruisers but at least in the US, did not have more endurance. They were more suitable for the sea denial and counter-sea denial missions that required high speed and long range gunfire, where a protective deck might help more than a waterline belt.

Smaller yet is the "third class cruiser" or "peace cruiser." This was designed to be the station ship in areas of low threat. These ships could be as small as 3,000 tons full load or even less, and they generally had light deck and localized gun armor, occasionally an armored conning tower, and sometimes even no armor at all. In the 1890's many of these had quite modest top speeds, being unable to reach even 20 knots. While in their peacetime roles this was not a handicap, it could certainly be a danger if war broke out, because against many possible opponents these ships could neither fight nor run.

The "scout cruiser" was about the size of a protected cruiser; its main unique feature was a higher speed. Scout cruisers introduced the tradition of quadruple screws for US cruisers. Dividing the propulsion thrust up among 4 propellers reduced propeller loading and the tendency to cavitate at extreme speeds. Therefore, quadruple-screw cruisers could have higher speeds without excessive draft, and continued to be produced through World War II. The most outstanding US scout cruiser was certainly the Omaha class, discussed in a later section. Once naval aviation began to provide float planes for use on cruisers and battleships, the scout cruiser's role declined in importance so that none were built after about 1925.

3.2 Shift from armored to unarmored

Cruisers did not, of course, evolve in a vacuum; they were affected by the development of other warship types. By 1890, the transition to steam and steel was complete in most navies. "Classical" solutions to most of the ship types had been arrived at by experimentation and analysis, aided by war game experience in the absence of actual combat. But the sea denial craft were still evolving rapidly, with surface torpedo boat speeds and seaworthiness increasing to the point that the British Royal Navy began to see these craft as a threat to the battle fleet. (While submarines had been successfully deployed by the Confederacy in the American Civil War, they were still experimental in the 1890's and did not become a serious threat until around 1900).

The British sought an antidote, a "torpedo boat destroyer," and in 1893 the first group of 250-ton boats was commissioned. These craft (later to be known as destroyers), had a designed top speed of 27 knots – faster than contemporary torpedo boats – and were also much larger and better armed. Now destroyers became in their turn a threat to (as well as a defense for) the battle fleet. Because the new craft were still relatively small and short range, they could not generally accompany the battle fleet on the high seas. Their existence became a factor driving cruiser designers to increase the speed of cruisers that might act as escorts to the battle fleet. This additional speed was generally achieved at the expense of armor protection and tended to drive designers towards lighter types of cruiser.

In 1906, the British Navy upset the status quo by introducing the battleship Dreadnought, which gave its name to the modern type of battleship with a uniform main armament of the largest caliber, assisted by a secondary, anti-torpedo boat battery of much smaller guns and later by antiaircraft guns. Dreadnoughts were also capable of higher speeds than previous battleships, using the newer technology of steam turbines and the advantage of larger size.

At about the same time as the Dreadnought battleship was introduced, the British Lord John Fisher also pushed the concept of the battle cruiser, a ship of higher speed but similar armament to the Dreadnought. Battle cruisers were the same size or somewhat larger than battleships, but with much reduced armor. In most navies that built them, they had 4 screws in a time period when battleships generally had 3 or 2. It is likely that Fisher intended the battle cruisers to serve similar functions to the scout cruiser, but by being essentially invulnerable to cruiser gunfire, to be able to do so even when opposed by enemy cruisers and destroyers. In addition, he probably recognized that a small unit of battle cruisers could perform maneuvers such as crossing the T of an enemy battle fleet while battleships prevented the enemy from concentrating fire on the battle cruisers. It was never intended that battle cruisers were, in classical terms, "fit to lie in the line", i.e. to trade broadsides with an enemy capital ship. But, perhaps because of their armament and styling – they carried battleship-sized guns, looked like battleships, and were at least as large – commanders did just that with them in World War I. But, they were not designed to survive battleship gunfire, and several of them blew up at Jutland (May 31, 1916).

The US did not complete a battle cruiser until much later; while several designs were developed during World War I, and one was approved in 1916, the Navy's bureaus absorbed the lessons of Jutland and the British Hood as the prototype of the fast battleship. ⁱ

However, the advent of battle cruisers changed the tactical environment for cruisers radically. The battle cruiser's battleship-size guns could hit at ranges no conventional cruiser could reach, and penetrate any armor short of a battleship's even at long range. Battle cruisers were faster than all but the fastest protected cruisers and of course the scout cruisers. If there was any possibility of meeting a battle cruiser, an armored cruiser was at severe risk.

This reality was exposed starkly by the First Battle of the Falklands, in December 1914, where a German squadron under Admiral von Spee, centered around armored cruisers Scharnhorst and Gneisenau, was practically annihilated by two British battlecruisers, Invincible and Inflexible.ⁱⁱ If cruisers in general were to be kept relatively small to maintain naval presence over huge areas, speed, rather than more armor and/or guns, was needed so that they could retreat when presented with an overwhelming threat like a battlecruiser. Accordingly, shortly before and during World War I, the armoring of cruisers decreased in favor of higher speeds. Some cruisers were produced with no armor at all; in many navies these were called "light cruisers."

However, armor of limited thickness still had a place in cruiser design. Performing the gunboat function, a ship might be exposed to small-arms fire or light artillery that could disable a ship far away from dockyards and supplies before much defensive action could be taken. Also, a cruiser must not be disabled by a single hit from destroyer-size guns.

3.3 Communications

Communications for cruisers and other naval vessels are of two fundamental types, short range for exchanging tactical signals between an embarked commander and other ships in the squadron and long range for receiving instructions from or reporting information to higher command.

During the day, tactical signals would usually be accomplished by signal flags, which had existed at least since the 1600's. Initially, colored lanterns or rockets were used at night. Around 1880, electric lights were introduced, using a searchlight-like beam interrupted suitably to transmit the same Morse Code used in the telegraphs, greatly improving night signaling. At this time, however, flag signals were still the primary means of daylight communication between ships.

Long range communications had historically been accomplished through the use of written communications (dispatches) carried by fast ships or later, through the use of telegraphed messages to foreign ports where they could be picked up by the ships (this was the method used to instruct Admiral Dewey that hostilities with Spain had commenced and to proceed to the Philippines). The next development was the evolution of "wireless telegraphy" or WT. A two-way radio could transmit or receive a keyed, Morse code signal from a shore station or another ship. This capability evolved gradually from the first experiments of Guglielmo Marconi in 1895 that required huge land-based towers to hold the antennas, gradually producing marine sets with (at first) very limited range, then gradually increasing performance. Radio started being installed on cruisers routinely around 1900, and was on board most naval ships by the start of World War I.

However, radio communication, while it greatly augmented the value of a scout cruiser, perhaps even making specialized scout cruisers worthwhile,ⁱⁱⁱ also created entirely new problems of command and control. In World War I, central naval commands and heads of state recognized that radio gave them the ability to give orders almost in real time to operational commanders. This put the at-sea commander in a difficult situation, that is, he could be blamed for taking independent action without consulting London or Washington, but he could also be blamed if he followed radioed instructions and the instructions proved to be ill-advised because central authority didn"t understand the situation on the water. Both of those situations developed in World War I, and a number of careers were ruined as a result.

In the maneuvers that led to the Gallipoli campaign, for instance, Vice-Admiral Troubridge decided not to engage the German battle cruiser Goeben with a force of cruisers. He was court-martialled, but acquitted based on the radioed orders he had received to avoid combat with "a superior force." However, he never got another sea command. ^iv

4. CRUISER DEVELOPMENT 1920-1938

The Washington Naval Treaty of 1922 significantly altered the progression of cruiser design in the United States. The Treaty caused what can roughly be thought of as a 16 year long detour in cruiser design stretching from 1922 to around 1938, when the looming threat of WWII effectively rendered the treaties established during the previous years no longer in effect. While the dissolution of the Treaty restrictions allowed unfettered design development, the cruisers developed post-1938 were largely derived from the Treaty-constrained Brooklyn Class rather than the pre-1922 battle cruiser designs scrapped by the Treaty implementation. Consequently the 16 year detour had far reaching implications extending well beyond 1938.

4.1 US Navy leading up to the Washington Naval Treaty

US Navy cruiser design in the years leading up to 1920 was focused on two main types of new cruisers. The first was a class of scout cruisers which would eventually become the Omaha Class; the second was a new class of battle cruisers which was started, but never completed.

4.1.1 Omaha Class

The US Navy continued the pattern of deliberately designing cruisers with slightly increased performance over comparable foreign designs. Before WWI, the average cruiser in the world's navies displaced less than 5,000 tons and was armed with a few 6-inch guns in open shields. The Omaha Class design was greatly superior to such craft in battery, speed, and range. The Omaha Class was designed specifically in response to the British Centaur Class cruisers. Although from a modern viewpoint a conflict between the US and Great Britain seems implausible, US Navy planners during this time and up to the mid-30's considered Britain to be a formidable rival for power in the Atlantic, and the possibility of armed conflict between the two countries plausible enough to merit appropriate planning measures.

Originally designed with eight 6-inch guns, this number was increased to a total of twelve during construction to counter the seven 6-inch guns aboard the Centaur. Ata design speed of 35 knots, the Omaha was the fastest ship in the world, a full 3 knots faster than its closest British rival.

Launched in 1920, the Omaha (designated C4 and later CL 4) had a displacement of just over 7,100 long tons. The cruisers emerged with a distinctly archaic appearance owing to their WWI-type stacked twin casemate-mount cannons and were among the last broadside cruisers designed anywhere.

As a result of the design changes placed on the ship mid-construction, the Omaha that entered the water in 1920 was a badly overloaded design that, even at the beginning, had been rather tight.^v The ships were insufficiently insulated, too hot in the tropics and too cold in the north. Sacrifices in weight savings in the name of increased speed led to severe compromise in the habitability of the ship. While described as a good ship in a seaway, the low freeboard led to frequent green water ingestion over the bow and in the torpedo compartments. The lightly built hulls leaked, so that sustained high-speed steaming contaminated the oil tanks with sea water.

These drawbacks notwithstanding, the US Navy took a great deal of pride in the Omaha Class. The Omaha placed a high emphasis on underwater explosion protection from the threat of torpedoes. She was designed with improved compartmentation while her magazines were the first to be placed on centerline, below the waterline.

Originally designed to serve as a scout, they served throughout the interwar period as leaders of fleet flotillas, helping them resist enemy destroyer attack. Tactical scouting became the province of cruiser aircraft, and the distant scouting role was taken over by the new heavy cruisers spawned by the Washington Naval Treaty. Thus, the Omahas never performed their designed function. They were relegated to the fleet-screening role, where their high speed and great volume of fire were most appreciated.^vi

Figure 1 C10 Concord

4.1.2 Pre-1922 Heavy Cruisers

While the successful fielding of the Omaha Class cruisers gave the US a slight advantage against the Centaur class cruisers, an additional threat to US Navy scout cruiser superiority loomed across the Atlantic which outmatched the Omaha's capabilities. The British Hawkins Class cruisers (1916) boasted seven 7.5-in/45 guns at a displacement of 9,750 tons at a sprint speed of 30 knots. The Hawkins was designed by the British to hunt down German commerce raiders, and had been given an unusually long-range weapon that might enable them to cripple such raiders before they could flee. This counter-raider had the unintended effect of upgrading foreign designs, partly because of its potential as a raider.^vii For the US Navy, the Hawkins became the standard for cruisers designed for independent operations, with planners demanding six 8-inch guns and a speed of 32.5 knots to counter the Hawkins capabilities. The designs produced by the US Navy which were formulated in response to the Hawkins Class would eventually lead to the USS Pensacola, the first of the so called "Treaty cruisers."

4.1.3 Pre-1922 Battle Cruisers

In 1909, as discussed in a previous section, the British Navy had already fielded another extremely powerful ship. HMS Invincible, the first battle cruiser, was designed to be superior to any normal cruiser then in existence. Invincible was armed with a battleship's big guns, while at the same time having a speed superior to both battleships and armored cruisers. Its role was to act as a superior scouting vessel, able to penetrate enemy cruiser screens while at the same time effectively screening her own battle force. She had secondary roles in hunting down and destroying enemy commerce raiders and in helping to reinforce the main battle line in a naval engagement.

In order to achieve the high speed necessary for the battle cruiser while carrying a sizable battery of heavy guns, the hull and machinery had to be bigger, more complicated, and more expensive than any vessel previously built. However, armor protection had to be kept to a minimum to reduce weight. Consequently, critics generally believed such a ship could not be used in a fleet action and was larger and more costly than necessary to carry out its other missions. Chiefly because of these criticisms, the US Navy hesitated for several years before committing itself to building battle cruisers.^viii

Apparent validation of the battle cruiser concept came early in WWI. In the First Battle of the Falklands, discussed in an earlier section, the superiority of the battle cruiser over the armored cruiser was clearly demonstrated.^ix

Development of a battle cruiser for the US Navy was very turbulent, with Navy planners following the capabilities of the British Navy, while Navy leaders wrestled with the political obstacles impeding the construction of the expensive and complex new class of ships. Originally envisaged with 14-inch main guns, the US battle cruiser designs were modified during the pre-Treaty years to overmatch the HMS Hood's 15inch guns with 16-inch guns. HMS Hood and the US Navy design were really more akin to fast battleships. The US design had stalked the British battle cruiser designs as they moved from the lightly armored HMS Invincible, shown to be particularly vulnerable to an encounter with a battleship, to the heavily armored HMS Hood.

Figure 2 Battle Cruiser HMS Hood

Six keels of the new battle cruiser class were laid during 1920: Constellation, Constitution, Saratoga, United States, Lexington, and Ranger. By the time they were begun it was already becoming clear to some of the more farsighted and politically oriented naval officers that they would probably never be completed. Construction lagged during 1921, and was nearly halted after the Washington Conference began its deliberations in November.

Thus begins the great detour in US cruiser production. It would be another two decades before the USS Alaska and USS Guam, the US Navy's first battle cruisers, would find their way into the waters of the Pacific Ocean just in time for the conclusion of WWII.

4.2 Washington Naval Treaty

On November 12, 1921, the five principal naval powers of the post World War I world convened in Washington D.C. to discuss naval disarmament. The United States, Great Britain, Italy, France, and Japan controlled the largest naval forces in the world at that time. Each came to the conference seeking an advantageous settlement. This was especially true in the case of the United States government, which wanted a naval disarmament agreement that could curb the capital ship arms race, particularly the increasing trend towards expensive battle cruisers, while also limiting Japanese expansion in the Far East.

The United States saw a potential threat from across both oceans. Britain had long been a dominant naval power, and was still warily regarded by naval planners all the way through the mid-1930's. The British controlled a far reaching network of colonies across the globe, which gave Britain many bases for naval operations. In a conflict against Britain, the US would have to steam considerably longer distances, with stretched supply lines. US planners hoped to curb the number of ships Britain was building, and also to maintain the tradition of having superior ships.

Japan was just becoming a threat. Japan's dramatic defeat of the Russian fleet in 1905 suddenly revealed Japan as a first class naval power. Although an ally during WWI, Japan's influence was steadily growing in the Far East, making US planners nervous about American interests around the Philippines.

To counter the Japanese, American naval strategists began planning for the development of naval bases in the Philippines and on Guam, in addition to the naval construction program authorized by Congress in 1916.

Realizing that their position in the Western Pacific was weak, the American military was forced to adopt a holding strategy. US Navy planners intended to be able to fight in two separate scenarios. The first was a two ocean war, with the US Navy on the offensive in the Atlantic, while on the defensive in the Pacific. The second was a one ocean war with the US Navy on the offensive in the Pacific.

The cornerstone of this strategy was the possession of a superior fleet, meaning a large number of battle cruisers capable of engaging and destroying Japanese cruisers. This was a cost that many American politicians were unwilling to underwrite. In this context, the Washington Naval Treaty can be seen as the lesser of two evils, with diplomatic intrigue replacing military might as the weapon of choice.

An agreement between the five powers was eventually reached, regulating the expansion of each nation's Navy. The most critical factor in allowing the Treaty terms to be agreeable to all of the parties was the genuine desire for arms limitations felt by all.

After specifying some exceptions for ships in current use and under construction, the Treaty limited the total capital ship tonnage of each of the signatories. The United States Navy and the Royal Navy could not exceed 525,000 tons, the French Navy and the Italian Navy were limited to 175,000 tons, and the Japanese Navy to 315,000 tons. No single ship could exceed 35,000 tons, and no ship could carry a gun in excess of 16 inches.

Aircraft carriers were addressed specifically with the total tonnage for carriers of the United States and the British Empire limited to 135,000 tons; for France and Italy 60,000 tons; and for Japan 81,000 tons. Only two carriers per nation could exceed 27,000 tons, and those two were limited to 33,000 tons each. The number of large guns carried by an aircraft carrier was sharply limited, meaning it was not legal to put a small aircraft on a battleship and call it an aircraft carrier.

As to fortifications and naval bases, the United States, the British Empire, and Japan agreed to maintain the status quo at the time of the signing. No new fortifications or naval bases could be established, and existing bases and defenses could not be improved in the territories and possessions specified. In general, the specified areas allowed construction on the main coasts of the countries, but not on smaller island territories.^x

This caused a change in strategy on the US side. Unable to further fortify the Philippines or establish a solid base on Guam, the US effectively gave up a strong permanent presence in the Western Pacific. This reduced land-based presence would have to be balanced by a greater sea based power projection.

All signatories pledged to maintain a balance in their respective capital fleets under a predetermined ratio:

• Britain 5

• United States 5

• Japan 3

• France 1.67

• Italy 1.67

The United States proposed to extend this ratio beyond just capital ships to apply to auxiliary ships, but was unable to get agreement from the other nations at the negotiating table.

Cruiser designs were capped at a maximum displacement of 10,000 long tons, with armament no larger than an 8-inch gun. (It is notable that these specifications correspond approximately to those of a Hawkins class cruiser.) While the aircraft carriers and capital ships were limited to a certain combined tonnage by the terms of the agreement, no such limitation was placed on cruisers.

The Treaty measured the displacement of the ships based on their 'standard displacement", a weight accounting methodology defined within the Treaty. The intent of the standard displacement was to avoid unfairly penalizing Great Britain and the United States for the large steaming distances the two countries required. Standard displacement did not count the weight of the fuel and reserve feed water needed for long range against the Treaty limits.

This had an immediate and dramatic effect on ship design within the United States. For the first time, weight estimation, control, and reduction moved to the forefront of design drivers for new ship designs. The US had not invested resources in investigating weight reduction measures in the years preceding the Treaty implementation. Additionally, US designers were suddenly trying to design a ship that would be just under the Treaty limits without fuel weight, while meeting speed and range requirements which are naturally tied to the amount of fuel onboard.

The bizarre effects of the Treaty were also evident in all of the US Navy conceptual designs coming after the Treaty's implementation. For each, the potable water, which might be excluded from standard displacement, was carried in the turret overhangs, and thus balance secured without added (Treaty) weight.^xi

The limitations on the cruiser displacement and armament were not arbitrarily assigned, rather they were a rationally arrived upon set of restrictions due to the world's intention to maintain parity with rival nations' capabilities. By this time the US Navy had two years of experience designing 10,000 ton, 8-inch cruisers and had convinced itself that nothing smaller was really worth building, considering Pacific distances. The British Hawkins class cruisers had already made the 8-inch gun cruiser the standard for long range cruisers in every nation, and agreeing to the 10,000 ton displacement limit and 8-inch armament limitation was naturally amenable to the US. This had the immediate, if unintentional, effect of simultaneously creating both an upper and lower bound of future cruiser designs. While the Treaty did indeed curtail the arms race of building capital ships, it inadvertently supplanted this contest with a new arms race of building "Treaty cruisers."

After the conference, cruisers carrying the 8-inch guns were re-designated as "Heavy Cruisers (CA)" because they carried the heaviest allowable armament under the Treaty limitations. The Omaha Class ships, with their 6-inch guns, were re-designated as "Light Cruisers (CL)."

The Treaty was one of the first steps of the United States Navy's conversion from a battleship fleet to an aircraft carrier-based force. The United States was over the limits in capital ships when the Treaty was ratified, and had to decommission or disarm several older ships to comply. The US was under the allowable tonnage for aircraft carriers since the only aircraft carrier in the US fleet before the Treaty was signed was USS Langley (CV 1), a converted collier. Not only did carriers have separate limits, but as an experimental vessel, Langley did not count against the tonnage restrictions.

Consequently, the US Navy had a free rein to build carriers, subject initially only to budget limitations. The decision was made to halt construction on the current fleet of battle cruisers and convert the USS Lexington and USS Saratoga to aircraft carriers. The Constellation, United States, Constitution, and Ranger were scrapped.

For the US Navy the Treaty did indeed limit the production of capital ships but escalated the production of heavy cruisers and carriers. Thus the Washington Naval Treaty had the fortunate effect of moving the US Navy towards carrier based warfare, though it would be several years before the full potential of this paradigm shift in ocean warfare was realized by the US and other Navies.

4.3 1^st Generation Treaty Cruisers

4.3.1 Foreign Activity

The British Arethusa class, completed in 1914, introduced a number of new features. This was a small cruiser of only 3530 tons, armed pre-dreadnought style with two 6-inch/45 guns fore and aft and six 4-inch guns in broadside. However, she had high speed turbine machinery and oil fired boilers, plus a novel weight saving feature: an armor belt that was built into the hull so that it contributed to longitudinal strength.^xii Armor is generally bolted to the ship's structure. The reason for this is that armor is generally not homogeneous: the outer surface is case-hardened using various chemical processes so that it has the greatest possible resistance to penetration, while below this hard surface the steel is maintained in a ductile condition to prevent the plate from becoming brittle and shattering if hit by a projectile that cannot be stopped by the surface. This process had different names and slightly different chemistry among the various producers of armor, such as "Harveyed" in Britain or "Krupp Cemented (KC)" in Germany. So as not to weaken the hardened surface, these plates needed to have a threaded rod screwed in from the rear into the ductile part. This rod could later be passed through a corresponding hole in a layer of teak backing and the ship's structural plating, then secured with a washer and nut. It was rarely practical to secure adjacent plates to each other, so belt armor was generally not watertight, and the backing and fasteners added weight.

But, by 1912, high tensile steel ("HTS", harder than mild steel through and through, but with substantial toughness as well) had become available. For light armor under 4", this worked nearly as well as case-hardened plates. The Royal Navy used HTS for Arethusa's belt, riveted firmly into the surrounding plating so that it was part of the watertight envelope of the ship. It therefore contributed to longitudinal strength, although this contribution was not huge since it was close to the neutral axis of the hull. The deck and bottom were the principal members of the "box girder" of the hull, when considered in longitudinal bending. The added stiffness provided by the belt allowed some degree of weight saving in the rest of the structure, but probably more by eliminating fasteners and backing.

The Arethusa was also the first British cruiser to be called a "light" cruiser; she later achieved fame as the flagship of Commodore (later Admiral) Sir Reginald Y. Tyrwhitt, CB, RN, commanding the "Harwich Force" of destroyers.

Japan received a visit by HMS Hawkins shortly after the war, and she made a huge impression. Accordingly, they adopted the 8-inch gun as the standard cruiser weapon, agreeing with soon-to-be-imposed Treaty limits.

In 1921 (before the Treaty took effect) they started building an innovative, experimental small cruiser, Yubari, that with a displacement of only 3309 tons, achieved 34.8 knots on trials and mounted six 5.5-inch guns and twin 24-inch torpedo tubes. Like Arethusa, this ship had armor used as a strength member.

In 1922 Japan placed an order for a larger Treaty cruiser, mounting six 20-cm (7.4-inch) guns, 3-inch side armor and 34.5 knot speed, all on 7100 tons standard displacement. Here too, armor was used as a strength member. The name-ship Kako came out overweight, barely within Treaty limits at 9540 tonnes standard. However, in spite of the extra weight, the two ships achieved their design speed on trials.

The British built their first class of Treaty cruisers in 1924-5, commissioned in 1928. This was the "County" or Kent class. They were 9750 tons standard displacement, armed with four twin 8"/50's, four 4"/45 AA, two quadruple 2-pdrs, 2 quadruple 21inch torpedo tubes, and later one seaplane apiece. Armor was extremely light, with a 1inch belt and additional 1 to 4 inch magazine box protection. The main armor was concentrated in a 1.375-inch protective deck. This lack of armor was a direct result of compromises inherent in the Treaty displacement limit coupled with the desire for high speed (31.5 knots on 80,000 SHP with 4 shafts.) The Admiralty had earlier wanted 33 knots, and the Director of Naval Construction (DNC) had intended to delete the belt armor entirely; the reduced speed and light belt were a compromise. (Why exactly the British chose to build a heavy cruiser so early in light of their later opposition to the type is somewhat mysterious.)

France authorized its Duguay-Trouin class of 3 cruisers in 1922 (commissioned 1926-7). They had eight 155-mm (6.1 inch) guns in twin turrets and made 33 knots on trials, but had practically no armor. At 7250 tons standard, 9350 full load, and carrying four 75mm secondary guns and twelve 21-inch torpedo tubes, they were well below Treaty limits and probably their lack of armor was the result of other considerations rather than Treaty compliance. They were heavily powered at 100,000 SHP, 4 shafts, even more than the US Omaha. Since they also had an advantage in length and were not much different in displacement, it is surprising they did not turn in a better trials speed. Endurance was only 3,000 miles at 15; Omaha claimed more than twice as much, but endurance figures in this period were frequently criticized as inaccurate.

4.3.2 Pensacola Class

If the General Board had strongly favored cruisers before 1922, the Washington Treaty greatly increased its interest in them. In effect the Treaty turned the 8-inch gun cruiser into a kind of junior capital ship. The old scouting role was, if anything, more important in the new kind of Pacific war the navy was then planning than it had been in the Atlantic. Perhaps as importantly, the prospect of losing a single capital ship out of the reduced number surviving under the Treaty would deter a commander from releasing single ships for such roles as convoy escort and shore bombardment. In WWI there had been many obsolete battleships and armored cruisers available for even the riskiest assignments, but they had been wiped out at the conference table. To fill their place, heavy cruisers, their numbers unlimited under the Treaty, would be required.^xiii

The General Board had evaluated a number of scout cruiser designs leading up to the Treaty limitations, and continued to evaluate alternatives up to 1924 with the authorization of the Pensacola. The General Board concluded that designs split into two categories depending on what function a cruiser would serve: protecting or destroying merchant ships, or operating with the fleet. Ships in the former role required a speed of 32 to 34 knots, in the latter, 27 to 32 knots. Although opinions on guns and protection differed widely, the Board did agree that aircraft were secondary.^xiv

By December 1924 there was enough evidence of foreign willingness to begin a cruiser-building race that Congress authorized eight new cruisers, the Pensacolas (CA 24-25) and the Northamptons (CA 26-31). The first of the Pensacola Class cruisers launched was the USS Salt Lake City (CA 25) on January 23, 1929, with a design displacement of 11,568 tons.

Figure 3 CA24 Pensacola

4.3.3 Northampton Class

The development of an alternative design to the Pensacola Class, which became the Northampton Class, began even before the Salt Lake City had been laid down. The new ships had two separate origins. First, there was a feeling within C&R that the Salt Lake City design sacrificed too much in order to mount the maximum battery, ten 8-inch guns. No great improvement in protection could be achieved, but it did seem possible to improve the balance between firepower and seagoing characteristics. That is, the earlier design had traded freeboard for extra guns. Reducing the armament to 9 guns had a big effect on weight, armor area, and volume because this battery could be mounted in three triple turrets, rather than requiring four turrets of two different designs. Also, the aircraft arrangements of the Pensacola Class were not entirely satisfactory.^xv

The other and driving impulse behind a new cruiser came from the General Board. In 1926, with funds for three new cruisers in prospect, it sought improvement over the existing Salt Lake City design to increase survivability.^xvi

There was considerable interest in habitability for the Northamptons. Volume studies showed an increase from the Salt Lake City Class of about 15% per man. The Northamptons were the first major US warships to be designed for bunks rather than hammocks. Objections were raised: bunks would encroach upon open spaces used for recreation, assembly, and shelter in bad weather, as well as upon mess spaces. Bunks above the second deck would be subject to splinter damage, though this danger was rationalized by Navy planners with a familiar ring to modern ears.^xvii

The rationale was that the crew should be at battle stations during action, and therefore the bunk spaces would be lightly, if at all, manned. The fraction of the ship's time spent at war was miniscule compared with the time spent during peacetime. In the event of war, the bunks could easily be removed and the sailors would put up with reduced accommodations as one of the obligatory sacrifices made necessary by war.

Even then, the Navy suffered from a high rate of desertion and poor reenlistment numbers. The improved habitability was one step in a far reaching effort to improve retention through quality of life that extends to today.

The first of the Northampton class cruisers, the USS Chester (CA 27), was launched July 3, 1927, with a design displacement of 11,574 tons.

Figure 4 CA 29 Chicago

4.3.4 The "Treaty Tinclads": Pensacola and Northampton Classes

The great irony was that, after the designs had been largely determined by the need to stay barely within Treaty limits, the ships came out grossly underweight, even after last-minute changes. The full load delivery displacement of 10,666 tons for the Salt Lake City was a full 900 tons underweight, the full load delivery displacement of the Northampton of 10,965 tons a full 600 tons underweight. This was a result of Preliminary Design's conservative estimating of the design weight and the concurrent implementation of the Northampton class, which was already being built by the time the weight shortage in the Salt Lake City was fully realized. As a result, the both classes had an excessive metacentric height. The roll was, therefore, both short and deep which caused a disconcerting motion.^xviii Very heavy snap rolling could even break the topmast, which was essential for long-range radio at this time. This happened to the Salt Lake City when she was en route from New York to Guantanamo early in 1931. Anti-rolling tanks were installed experimentally in the Pensacola and the Northampton. The tanks were not interconnected, rather, the tank on each side was open to the sea, with a vent pipe.^xix There were also complaints of weak sternposts and excessive vibration aft at high speed, presumably due to weight savings in the hull structure and cured by structural stiffening. The ships seemed light, with serious damage inflicted on the hull of the ship when the three guns of a turret were fired together.^xx Thus the first two cruiser classes emerging from the Washington Naval Treaty were informally dubbed "Treaty tinclads."

The 8-inch gun cruisers brought a new capability to the fleet when they entered the service. They replaced the elderly battleships of the Scouting Force and served not merely as scouts but, perhaps much more importantly, as escorts for the new fast carriers in independent task force operations. Another role these cruisers could fill was that of fleet flagship. The first three Northamptons were built as division flagships. The last three were fleet flagships.

4.4 2^nd Generation Treaty Cruisers

4.4.1 Portland Class

Almost from the first, there was certain dissatisfaction with the very limited protection of the 8-inch gun cruiser. As it became evident that more weight was available than had originally been estimated, protection was improved as much as possible in the ships still under construction.^xxi The Portland Class, originally slated as CA 32-36, was in effect an upgraded version of the Northampton Class cruisers. The first Portland Class cruiser launched was the USS Indianapolis, on 7 November, 1931. She had a design full load displacement of 11,574 tons, a speed of 32.5 knots and an endurance range of 10,000 nm at 15 knots. Her main battery consisted of nine 8-in/55 guns and an anti-aircraft battery of eight 5-in/25 guns and eight 0.50 caliber machine guns. She actually came in heavy at a full load delivery displacement of 12,755 tons.

Figure 5 CA 35 Indianapolis

4.4.2 New Orleans Class

The follow on group to the Portland Class cruisers, CA 37-41, exhibited such superior characteristics, that an attempt was made to reorder CA 32-36 to its specifications. However, two ships, the Portland and the Indianapolis had been awarded to private builders and contract changes would be far too expensive. The remaining three ships were all at Navy yards and could be modified without great expense. Thus the Portland Class was relegated to just two ships, while CA 37 became the lead ship for the new New Orleans Class cruisers. The New Orleans Class cruisers corrected the weight estimation deficiencies of the previous classes, and formed a much better protected and balanced cruiser design. The New Orleans Class was the first US cruisers built without torpedo tubes due to war gaming results from the Naval War College which indicated that the torpedoes were unlikely to be fired from a cruiser, and more a liability than an asset. (These academic results were contradicted a number of times during World War II, when both Japanese and British cruisers used torpedoes rather effectively). The first ship of the New Orleans class launched was the USS San Francisco, on March 9, 1933. She had a full load displacement of 11,585 tons, a design speed of 32.7 knots, and a design range of 10,000 nm at 15 knots. She had a main battery of nine 8inch/55 guns and an anti-aircraft battery of eight 5-inch/25 guns and eight 0.50 caliber machine guns.

Figure 6 CA 38 San Francisco

4.5 Geneva Summit and the London Naval Treaty of 1930

The heavy cruiser race began in earnest in 1922 with Japan's announcement of a major construction program of cruisers, destroyers, and submarines. The British, Americans, French and Italians soon followed suit. The first attempts to curtail the buildup began in 1925 through the League of Nations. These talks and a second series of talks in 1927 in Geneva both failed. The United States and Britain were fundamentally at odds on the issue of heavy cruiser buildup.

The British preference was for smaller cruisers because they were easier to build and maintain across the vast British Empire. The existence of heavy cruisers was an obvious threat to a predominantly light cruiser oriented British fleet. The British did, however, need heavy cruisers for working with the fleet. Therefore, their position was not to eliminate the heavy cruiser, but to limit its numbers.^xxii

For the American fleet, trade protection was not a major consideration. The US needed to maintain naval communications out to the Philippines in the Far East. Large cruisers were vital, since American refueling facilities and naval bases in the Pacific were few. The American position was to maintain the current restrictions set forth in the Washington Naval Treaty, but to control escalating costs by restricting the numbers built by the negotiating navies. ^xxiii

The Japanese had very little use for light cruisers as trade protection was not a major concern. They instead required cruisers which could work with the fleet. The Japanese wanted parity with their American and British counterparts, and to maintain the Washington Naval Treaty restrictions concerning heavy cruisers.^xxiv

In the interim between the failed Geneva talks of 1927 and the London Naval Treaty of 1930, several key compromises were worked out between the negotiating parties. The United States agreed to restrict its total number of heavy cruisers to 18, and build the remainder of its tonnage allowance in light cruisers. Japan gained a higher ratio of 10:7 against the American and British light cruisers and destroyers, and maintained the 10:6 ratios in heavy cruisers. The maximum armament allowed for subsequent light cruisers was set at 6-inch guns and maximum displacement 10,000 tons.

4.5.1 Flying-Deck Cruisers

As part of the Washington Naval Treaty, the battle cruisers Saratoga and Lexington were both converted into aircraft carriers. Unfortunately, these ships together used up nearly half the carrier tonnage quota allowed to the US Navy under the Treaty, so that less tonnage remained for future construction. Furthermore, a frugal Congress kept naval appropriations so small that no new carriers could be built. The result was that the Navy, well aware of the potential of the aircraft carrier for scouting and attack duties, began to consider aircraft carrier/cruiser hybrids. Given that resources were too scarce to have both, the hope was to combine the best features of both ship types into a single cruiser class.^xxv Within a few months of the conclusion of the London Naval Treaty, the Bureau of Construction and Repair was working on plans for what was called a flying-deck cruiser. The design was to incorporate as much carrier capability as possible while sacrificing the least amount of cruiser capability. All of this in a ship whose displacement could not exceed 10,000 tons.^xxvi

With the election of Roosevelt and the implementation of the "New Deal", specifically manifested in the National Industrial Recovery Act of 1933, the US Navy suddenly found itself in the unexpected position of no longer needing to compromise between carriers and cruisers. Given the funds necessary to build both types of ships, the flying-deck cruiser idea was scrapped.

4.5.2 Erie Class Gunboats

The Erie Class gunboats were an updated version of the old peace cruiser with important additional wartime roles. It is because these gunboats had a role usually filled by a cruiser that they are worth some mention in this report. The roles the new gunboat would fill in a wartime setting were listed by Captain Ingersoll of Fleet Training as antisubmarine and anti-destroyer screening, high-speed minesweeping ahead of the battle fleet, tactical control of fleet submarines, plane guard duty for slow carriers, support of destroyer attacks made from ahead of an enemy fleet, convoy warfare, and fire support of amphibious operations.^xxvii Unfortunately the Erie Class was too slow to perform most of these functions. Although the ships were intended to spend most of their service in Asiatic or Caribbean waters, their design was governed by their proposed semi-cruiser employment in wartime. The Erie was designed to embark an aircraft because of the needs of the Asiatic station. The Erie Class gunboats could augment the dwindling number of tender-based aircraft. The hull was designed with a wide transom to facilitate minelaying or for carrying depth charges, while the rake and sheer of the bow resisted green water. Diesel propulsion was considered but abandoned in favor of steam turbines because the turbines would fit in a smaller space, and Erie was a tight design. One of the problems the General Board had in choosing a final design for the Erie Class concerned armor: did an armored ship violate the letter or the spirit of the Treaty?

The board convinced itself that it was allowed by their interpretation and the Erie was designed to allow the ready addition of a 3 inch side belt in time of war. While it appears the belt was not fitted at delivery^xxviii, photos from the war years seem to show it.

The Erie class was not particularly successful. It consisted of only 2 ships; the name-ship was torpedoed in November 1942 and after being towed to harbor, capsized and became a total loss. Considering how small a ship this was, loss to one torpedo hit does not reflect badly on the design. The sister was decommissioned in 1946 after only 10 years of service.

4.5.3 Brooklyn Class Light Cruisers

The London Naval Treaty (1930) had the immediate effect of triggering construction of the first seven Brooklyn Class light cruisers. These cruisers and the Brooklyn based design for the Wichita mark a defining moment in US cruiser design. Previous cruisers had evolved steadily under the limitations of the Washington Naval Treaty while the cruisers to follow would be unfettered by Treaty limitations. The Brooklyn Class undoubtedly would never have been built were it not for the influence of the London Treaty of 1930. The US Navy suddenly found itself in the difficult situation of being obligated to build 6-inch gun cruisers regardless of the military value of such ships. Absent the 1930 Treaty, there is little doubt that the US Navy would have preferred improved 8-inch gun cruisers.

The legacy of the London Treaty of 1930 stretched far beyond the Brooklyn Class. Both major wartime classes, the Clevelands and the Baltimores, share a direct lineage with the Brooklyn Class cruisers. This influence was principally channeled through the Wichita, an 8-inch Brooklyn Class variant. Consequently, the unrestricted wartime cruisers were heavily based on the Treaty-restricted Brooklyn Class ships.

Following the ratification of the London Naval Treaty, C&R began a study of possible 6-inch gun cruiser designs. They were to have a speed equal to the 8-inch gun cruisers with as near a range to the 8-inch gun cruisers as was possible. Acceptance of the US Navy eighteen ship limit stipulated in the 1930 agreement hinged on C&R estimates that showed a well designed light cruiser could strike an acceptable balance between guns and protection. C&R believed the ship could be made to stand up to heavy cruiser fire, while retaining adequate armament. This was based on the concept of "Immune Zone" protection, an idea which seems to have originated in the US Navy during or shortly after World War I. It was originally applied to capital ships.

The immune zone was a range band within which a ship's armor was intended to defeat enemy projectiles, as shown in Figure 7. For example, a certain cruiser might have armor designed to protect it against 8-inch shells from 15,000 yards to 22,000 yards. This means that for direct fire closer than 15,000 yards, an 8-inch shell was expected to have enough energy to penetrate the ship's side armor, but beyond 15,000 yards it did not. Beyond 15,000 yards, the shell would not have enough energy to penetrate the armor until the trajectory of the shell became so steep so that, as it plunged out of the sky, it had enough energy to penetrate the armor on the deck. This happens at 22,000 yards in the example. At 21,000 yards, a shell may hit the deck, but the angle of impact and the armor on the armored deck were expected to be sufficient to prevent it from penetrating into the ship's vitals. Also playing into the calculation of required protection was the range at which accuracy of the fire controls made hits so rare that protection at certain ranges was not warranted.

Figure 7 Immune Zone

The General Board desired a new cruiser with overmatched protection, a ship with protection against armament larger than her own. This was essential due to the number of 8-inch gun cruisers already in service with other navies which could handily defeat a 6-inch gun cruiser designed for protection against her own armament. The US Navy believed a 6-inch gun cruiser could be designed with acceptable armament while remaining protected from 8-inch shells from a heavy cruiser. Indeed, as previously mentioned, this was the catalyst which provided US Navy acceptance of a limit of eighteen heavy cruisers, with all additional restricted to 6-inch gun maximum armament.

A number of candidate designs were developed for the new class of light cruisers. The fundamental dilemma imposed by the naval treaties was determining the right balance between capability (i.e. displacement) and numbers of ships. The US fleet would have widely differing characteristics were all of the Treaty tonnage allowance used on a large number of 6,000 ton ships versus fewer but more capable 10,000 ton ships. Also competing for Treaty tonnage would be the possible flight-deck cruisers, limiting the number of true cruisers. Admiral Pratt, the CNO, wanted experimental flight-deck cruisers and large numbers of smaller cruisers. He believed that cruisers should be used as rangers with the Scouting Fleet or with the Battle Fleet and would be able to retire back to the protection of the main fleet once they had secured the necessary information. Friedman^xxix notes that this view seems slightly odd in view of the later concern for using small cruisers as an anti-destroyer screen for the battle line, and in view of Pratt's feeling that aircraft had displaced cruisers as the primary scouts.

The studies that brought about the genesis of the Brooklyn Class were prepared in response to the Japanese Mogami Class light cruisers. The Japanese announced they would mount fifteen 6.1-inch guns (5 triple turrets) on a new cruiser that would make 37 knots at 8,500 standard tons. To accomplish this feat, Japanese designers resorted to the latest weight saving techniques, including light alloys in the superstructure and electric welding. On trials in 1935, the first two ships of the class had numerous problems. Firing the guns caused the welded seams to open, and the turrets frequently jammed because of deformation in the hull girder. Worse, the ships were dangerously unstable and some of the antiaircraft guns had to be removed. Later, they were bulged to regain a safe degree of stability, and full load displacement grew to 11,200 standard tons (beyond Treaty limits) with speed dropping to 35 knots.

It never seems to have occurred to anyone at the time what would happen if a ship was over the Treaty limit at delivery; the answer, it soon developed, was nothing. This "loophole" was exploited more or less dramatically by most of the navies of the interwar period. The Mogami class "cheated" in another way: their turret mountings were designed to accept 8-inch twin turrets in place of the triple 6.1-inch to get around the Treaty limits on heavy cruisers. This modification was performed before the war.

However incorrect the declared specifications were, the announcement had the immediate effect of galvanizing the US Navy and setting the new design acceptable armament at a minimum of fifteen 6-inch guns. Previous studies had shown a smaller number of guns, around twelve, would result in a better balanced ship. These results were discarded in light of the new threat, and protection was to be sacrificed for increased armament, not speed.

This was a reversal of policy from heavy protection and moderate gun power towards heavy gun power at the expense of protection. The US delegation at the 1930 London Naval Treaty had accepted the Treaty limitations on the assumption that a 6inch gun cruiser could be made to engage an 8-inch gun cruiser with some prospect of success, under the right conditions.

However, changes since 1930 had led to improved 8-inch gun cruiser designs to a point where guns, machinery, and magazines could be adequately protected within the 10,000 ton limit. Conversely, it was apparent that no fifteen gun light cruiser could be made with protection against attack by existing heavy cruisers. A twelve gun light cruiser design showed a very small, 1,600 yard immunity zone against 8-inch shells, with possible improvement with design refinement.

The designs submitted by Preliminary Design in response to the new direction made concerted steps towards reducing weight as much as possible to be placed back in as increased protection. Preliminary Design estimated that 280 tons could be moved towards protective measures by using longitudinal framing, and more general use of high-grade steels. This foreshadowed the more daring weight control program eventually incorporated during design. Weight reductions, however, were somewhat counterbalanced by the emergence of a new long 6-inch shell which threatened new designs with increased direct fire penetration power than previously assumed. Speed was held constant at 32.5 knots for all designs with armament and protection traded between various twelve, fifteen and sixteen gun schemes.

The final decision was solidified by a comparison between the twelve and fifteen gun US designs against the Mogami. The fifteen gun light cruiser was shown to be superior to the twelve gun light cruiser against the Japanese design, according to Naval War College analysis. Thus, the decision was made that the new Brooklyn Class cruisers would mount fifteen 6-inch guns.

The design of the Brooklyn cruisers differed sharply from existing US cruisers. They incorporated aft aviation features that were copied on all following heavy and light cruisers, excluding the Alaska. They also incorporated longitudinal framing as a weight saving measure. They were the first ships in the fleet to be designed with the new 6-inch gun firing semi-fixed ammunition, a precursor to the automatic dual-purpose weapons introduced in the late WWII Worcester and Des Moines Classes. Increased protection was evaluated by lowering speed to 30 knots, but this was rejected since the slower ships would be unable to operate in formation with existing cruisers.

The weight saving pessimism seen on the Portland and New Orleans designs gave way to an undue optimism causing weight saving measures to be compulsory to stay beneath the 10,000 ton limit as the ship was further refined. The forward belt was omitted and the acceptable hull stresses increased to further shave structural weight. The first seven Brooklyn cruisers (CL 40 – 43, CL 46 – 49) were built to this design.

Figure 8 CL 43 Nashville

The first of the Brooklyn Class cruisers launched was the USS Brooklyn on November 30^th, 1936. She displaced 11,581 long tons full load at a length of 608 feet overall.

The General Board considered next building a new class of cruisers with less displacement and armament, but a repeat of the Brooklyn Class was ultimately decided upon. CL 49–50, USS St Louis and USS Helena, were constructed as the final hulls of the Brooklyn Class. Friedman^xxx quotes the General Board in explaining their decision to repeat the Brooklyn Class rather than a reduced capability ship as follows:

"Since the question of numbers is necessarily regulated by the total tonnage allowed and since that total tonnage after 1936 is largelyindefinite owing to the uncertainties of the 1935 Conference, the Board considers that for now the properties of the individual ship are of greater importance than the number of ships."

This was a fortunate decision given that the 1935 conference would limit new cruisers to 8,000 tons standard, with no concurrent total tonnage limit.

The St Louis and Helena differed from the Brooklyn Class in a few marked ways. They mounted the new 5-in/38 guns, rather than the 5-in/25. They differed in internal machinery arrangement with two separated engine rooms made possible by smaller boilers using higher pressure, higher temperature steam. Because of these modifications, CL 49 & 50 are usually referred to as the St Louis Class cruisers. The St Louis was launched April 15^th, 1938. She displaced 11,790 long tons full load at a length of 607 feet overall.

The Brooklyn class was received favorably by the fleet. The rapid fire 6-inch guns received wide acclaim in the ship reports coming back to Navy Headquarters. Seakeeping was also reported to be excellent. However, it soon became apparent that in the name of weight saving, the structural integrity of the ship had been overly compromised. The Savannah ran over her anchor chain in a gale which sliced through her bow, causing severe damage. This led to a weakening of confidence in the survivability of the design among the fleet.

4.5.4 USS Wichita

Under the 1930 Treaty, a new heavy cruiser could be laid down in 1935. This was to eventually be the USS Wichita, a design based on the Brooklyn Class, 600-foot waterline hull, unlike (and longer than) any of the previous US heavy cruisers. She foreshadowed the Baltimore Class "production" heavy cruisers of WWII.^xxxi

In 1934 a modified Brooklyn design was proposed which would mount 3 triple 8inch turrets, increase steaming radius, upgrade the secondary battery, and incorporate aviation aft. She was expected to have better stability and survivability owing to her smaller main compartments and greater freeboard.^xxxii Protection was increased throughout the ship. The advantage of split salvos in minimizing dispersion was also recognized around this time and the Wichita's 8-inch turrets were designed specifically to permit the guns in it to be loaded and fired separately. The Wichita was launched November 16^th, 1937 at a displacement of 11,581 long tons full load and a length of 608 feet.

The Wichita was a one of a kind design, but greatly influenced following heavy cruiser designs starting with the Baltimores, which started as improved Wichitas.

Figure 9 CA45 Wichita

4.6 The End of the Treaty Limited Cruisers

The 1930 London Naval Treaty had specified that in 1935 another naval conference should be held between the parties. As talks began, a clear delineation became apparent with the Anglo-American parties aligning against Japan's demands for full parity. Japan walked out of the talks in 1936, leaving the United States, Great Britain, and France as the only signatories of the 1936 Treaty.

The failure of Japan to abide by the Treaty's qualitative restrictions in building programs led the signatory powers to invoke the escape clauses in the Treaty. By 1938 the 1936 Treaty was effectively no longer in effect and, since the 1930 Treaty had lapsed in 1936, naval limitations of any kind no longer existed.

By 1938 Hitler and Mussolini were firmly in power and headed on a direct course for war in Europe. In the East, the steadily growing threat of Japanese Imperialism loomed larger with each passing month. It is into this world that the United States emerged from the naval limitations treaties, and began its steady slide into the global conflict soon to erupt across the globe.

4.7 Inter-War U.S. Fleet Organization and Cruiser Employment

After WWI, the United States concentrated its main battle fleet (the United States Fleet) in the Pacific, anticipating that the major future threat was Japan. By the time war broke out, the heavy cruisers were primarily assigned to the Scouting Force and the light cruisers to the Battle Force. Both were organized into divisions of three to five ships each commanded by a rear admiral. Each of the destroyer flotillas (made up of multiple destroyer squadrons) had a light cruiser assigned as the flotilla flagship.^xxxiii

When this organization was adopted, the tactical doctrine was that the heavy cruiser was more versatile and suited by its heavier armament to range ahead in a scouting role and was assigned to the Scouting Force. After the enemy force was found and the fleet was getting ready for battle, the heavy cruiser took its place in the outer screen. The light cruisers stayed closer to the battle line to help defend against torpedo attacks by enemy destroyers. In this role the volume of fire from the six inch guns was more important than the greater weight and range of the eight inch gun.

At the same time, the relatively soft aircraft carriers, also assigned to the Battle Force, were originally planned to stay to the rear of the battle line where they would be safe. However, as a result of fleet exercises and experimentation, it was discovered that the best use of the aircraft carriers was to seek out and destroy the enemy carriers, thereby blinding the enemy commander. To do this, it was necessary for the carriers to operate independently and ahead of the battle line to scout for the enemy. The concern was that the carriers would encounter the enemy's heavy cruisers at night or under some other condition where they could not use their aircraft to protect themselves. The Lexington and Saratoga were initially armed with eight-inch guns for just this reason.^xxxiv The answer ultimately adopted was a task force organization where a division of heavy cruisers was assigned to each carrier group.

A smaller group of ships, the Asiatic Fleet, represented the U.S. interests in the pre-war Far East. Most of its units were based in the Philippines (at the time a U.S. colony) but it also included the Yangtze Patrol and the Fourth Marines, both based in China.

Through the 1930's and until the Asiatic Fleet ceased to exist in 1942, one modern heavy cruiser was the heaviest unit assigned and served as the flagship. The USS Houston and USS Augusta alternated in this role. Both ships spent a significant amount of time in Chinese waters, showing the flag and on occasion landing Marines and sailors to protect U.S. interests. They also visited other countries in the region including Japan a number of times. On one of these visits, the Augusta represented the United States at the state funeral of Admiral Togo, the hero of the Russo-Japanese War. As war between the Chinese and Japanese erupted in Shanghai, the Augusta observed at close range and sent back intelligence reports on Japanese capabilities.^xxxv In addition to the heavy cruiser, the Asiatic Fleet had one light cruiser of the Omaha class assigned.

5. CRUISER DEVELOPMENT WWII

5.1 Foreign threats

The major foreign threat concern of the U.S. was Japan. It was assumed that if war came, the U.S. would be fighting Japan in the Pacific without other allied support.

As previously discussed, the treaties agreed upon between World War I and World War II were intended to limit the potential naval arms race between the U.S., Great Britain, Japan, France, and Italy (Germany's navy was limited by the Treaty ending WWI). While the U.S. stayed strictly within the Treaty limits, Japan exceeded the limits by as much as 30 percent.

The British followed their Kent and similar London classes with a smaller heavy cruiser with only three big gun turrets. This allowed, on a standard displacement of 8390 tons, for a 3 inch armor belt and other improvements. Two ships were built; one, Exeter, was later to achieve lasting fame in the Battle of the River Plate. The Royal Navy's need for large numbers of cruisers for commerce protection and Imperial defense led them to create a large class of light cruisers, the Leanders, of which nine were built starting in 1933. They had four twin 6-inch/50's as main armament, a top speed of 32.5 knots, and varied between 6985 and 7270 tons standard. Once the total tonnage of cruisers was limited by Treaty, the British reduced the size of this design to create the Arethusa class, of which six were built at 5250 tons, using the same technique that had worked with the County's: eliminating one turret. Once the Mogami's capability became known, the British went into panic mode and built two maxed-out, 9100 ton (standard) light cruisers with twelve guns, Southampton and Newcastle, starting in 1937. More were built after war broke out.

These British cruisers were Mahan's "far distant, storm-beaten ships" in WWII as they had been in WWI, enforcing the blockade and stopping raiders. While the English Channel could be sealed off by light forces and mines, the wide straits to the north of England were covered by cruiser patrols, since only a cruiser size ship could remain on station for long periods in the brutal North Atlantic weather. The cruisers were well armed enough to directly take on armored merchant raiders or German cruisers. They also had enough sea speed to shadow larger units while calling on the main fleet such as when the Suffolk and Norfolk detected and tracked the Bismarck.

Drawing on his personal experience serving on a Royal Navy cruiser in WWII, the novelist Warren Tute (The Cruiser, 1955) attempted to define a cruiser to his layman readership with the quote in Table 1.

France had followed the Duguay-Trouin's with a similar heavy cruiser, Duquesne. This two ship class, commissioned in 1928, had 8-inch guns in the same arrangement as their predecessor, but with the hull enlarged to 10,000 tons standard, 185m (606.95") LBP, to support the heavier weapons and more AA guns. Speed was 33.75 knots on 120,000 SHP (exceeded on trials). Like the light cruisers, they had no armor, just a box of 30 mm plate around each magazine. The follow-on Suffren class, commissioned starting in 1930, kept the same hull dimensions but traded off engine power for additional protection compared to the earlier class. The French also completed the Algerie in 1934 with better protection and an improved eight-inch gun.^xxxvi

Italy's Fiume class, commissioned in 1931, was of 11,680 tons standard, but the government simply did not admit they had exceeded the limits. These were probably the first cruisers to cheat outright on the Treaty. They were armed like the French heavy cruisers with four twin 8-inch turrets, but much better protected.

Japan's Myoko class (1929) also exceeded Treaty limits at 10,940 standard. With her ten 8-inch guns, eight 5-inch/40 DP guns, and 34-knot top speed, these were formidable warships. The Japanese authorities were so happy with them that they refused to reduce any of their capabilities for the next class, Takao, and accordingly it exceeded the limit by even more at 11,350 tons (1932).

Germany rearmed steadily as it was allowed by the Versailles Treaty ending WWI, commissioning the light cruiser Emden in 1925. This was a 5600 standard ton ship with eight 5.9-inch (15cm) guns, some mounted in broadside like a WWI cruiser, and four torpedo tubes, with a top speed of 29 knots and a range of 5300 nm at 18 knots. The next class, Konigsberg, was almost 1000 tons larger; the Germans took advantage of the definition of standard displacement from the Washington Treaty to allow them to build bigger ships than the Versailles Treaty intended. These ships also made extensive use of welding as a weight saving measure.^xxxvii But, these ships were overloaded with three triple 5.9's and were not successful. Then in 1929 the Germans started work on the Deutschland class, a 10,000 ton ship with 11-inch (28-cm) guns in two` triple turrets. The size and armament of this ship was limited by the Versailles Treaty, and Germany was trying to get around these limitations. Therefore, it is hard to say exactly what this ship should be called; armored cruiser seems the closest, since she was too slow at 26 knots to be a battle cruiser. The Germans used the word "panzerschiffe" which just means armored ship. The British called them "pocket battleships." Diesel powered, these ships (3 were built, commissioned starting in 1933) had ranges of 10,000 miles, enough to be a formidable commerce raider. The three ships were slightly different in dimensions, the later ones being beamier and even heavier. Then after the Nazis took over Germany in 1933, the Admiral Hipper class heavy cruisers were built, conventional units with four twin 8-inch turrets but, at 13,900 tons, far beyond their claimed Treaty displacement.

The French, understandably worried about the German buildup, created a croiseur de combat, literally a battle cruiser, of 26,500 tons standard, and well-armed with two quadruple 13-inch/50 turrets, capable of nearly 30 knots but with only 9-inch armor. Commissioned in 1937, these Dunkerque class ships had both the speed and firepower to overwhelm a Deutschland, but they were about twice the size and cost.

The Germans responded to this development by scrapping the last two of the Deutschland class panzerschiffe, called D and E in official sources, and after a major redesign, laying new keels in 1935. These were to become the much larger battleships Scharnhorst and Gneisenau (not to be confused with the WWI armored cruisers of the same names), 26,000 tonnes standard (31,500 at delivery), with full battleship-scale armor such as a 350-mm belt (13.8 inches, more than the USN's Iowa class battleships).^xxxviii These ships are sometimes called battle cruisers because their big guns were of smaller caliber than battleships serving in other navies at the time, but because of their full battleship protection it seems more correct to call them battleships, as German sources do. Their top speed of 31-plus knots made them faster than most contemporary battleships but slower than most cruisers. Hitler had earlier renounced all restrictions on military rearmament. Later German warship construction included two units of an even larger Bismarck class of battleships, 41,700 tonnes standard displacement with 15-inch guns. These were commissioned in 1940 and 1941, and for the first time since WWI, gave Germany capital ships that were at least equal to any in the world. However, German war strategy was to use even their capital ships as commerce raiders, more of a cruiser function as described earlier.

5.2 Wartime roles and missions

World War II was, in many respects, two wars fought at the same time. The war in Europe and the Atlantic was primarily a land war with the Navy either protecting convoys, searching for and sinking submarines and surface raiders, and providing naval gunfire and other support to the landings in Africa, Italy, and France. The Pacific war, on the other hand, was primarily a naval war as the US and Japanese navies fought to gain or maintain control of the islands from Japan to Australia.

In the Atlantic theater, the cruisers, along with destroyers (DD) and escort carriers (CVE), provided defensive screening support to Allied convoys and task forces. Cruisers played a huge role in hunting down German surface commerce raiders, a classic cruiser mission (counter-sea denial). From the beginning of the war in 1939, three British cruisers (two light and one heavy) fought the Deutschland-class Admiral Graf Spee to a standstill in the Battle of the River Plate. Other British cruisers played important roles in hunting down the battleships Bismarck in 1941 (with HMS Dorsetshire actually torpedoing the sinking wreck) and Scharnhorst in 1943. The cruisers provided naval gunfire support to all the allied landings beginning with the landings in Africa. During the African landings the cruisers engaged and neutralized the French ships located in a nearby harbor. They also engaged the Italian Navy ships in the Mediterranean. They provided naval gunfire support as well as antiaircraft support to the landings in North Africa, Italy, and at Normandy. The USS Augusta, CA 31, served as President Franklin Roosevelt's personal flagship for his meetings with Winston Churchill at the beginning of the war in Newfoundland, and with Churchill and Stalin at Yalta near the end of the European war.

In the Pacific, the U.S. cruisers fulfilled multiple roles: fleet and task group flagships, carrier/task force screening, convoy escort and protection, surface task forces, naval gun fire support for the marine and army landings, and some merchant interdiction.

In the Solomon Islands, the loss of the American battle line at Pearl Harbor lead to cruisers being the heaviest U.S. units available to face the Japanese forces (in some cases including battleships) trying to attack the U.S. forces ashore at Guadalcanal. This lead to some extremely heavy losses until improved tactics using radar and properly coordinating the cruisers and destroyers were developed. Subsequently as U.S. forces moved up the islands driving the Japanese forces back and establishing naval and air bases in the islands the cruisers were a major source of naval gunfire support to these island invasions as the war moved across the Pacific. In the north Pacific the Japanese had occupied a few of the western Aleutian Islands threatening to move down the island chain and possibly attack mainland U.S. targets. This advance was stopped and the Japanese invaders were eventually forced off the islands. The naval support for this effort was primarily by surface task forces without carriers led by cruisers.

During WWII, most cruisers carried four Curtis SOC Seagull floatplanes (two on the catapults and two in the hangar). The SOC was a biplane and rather old but was more suitable for cruisers than the more modern OS2U Kingfisher because it had folding wings.

The floatplanes had several different roles. Even though the function of scouting for the enemy fleet had largely been taken over by carrier based aircraft, they were still used for anti-submarine patrols around the task force. Other missions included delivering messages during times of radio silence, towing target sleeves for anti-aircraft practice, rescue of downed pilots and of course gunfire spotting for the cruiser. When escorting a carrier though, if an air attack was expected, flight operations were curtailed because the maneuvering required for launch and recovery would reduce the effectiveness of the anti-aircraft fire.^xxxix

One cruiser, USS Indianapolis CA 35, played an important part in the end of the war in the Pacific. Following battle damage repairs in Mare Island, CA the Indianapolis received orders to proceed at high speed to Tinian, carrying parts and nuclear material to be used in the atomic bombs which were soon to be dropped on Hiroshima and Nagasaki. Due to the urgency of her mission, Indianapolis departed San Francisco on 16 July, foregoing her post repair shakedown period. Stopping briefly at Pearl Harbor 19 July 1945, she raced on unescorted and arrived Tinian 26 July, having set a record in covering some 5000 miles from San Francisco in only 10 days (an average of 21 knots).

During the war the US Navy lost ten cruisers, seven heavy cruisers (CA 26, 29, 30, 34, 35, 39, and 44), and three light cruisers (CL 50, 51, 52). All but one of these losses was in the area of the Solomon Islands during the struggle for control of those islands. All these cruisers were sunk by hits from the Japanese Long Lance torpedo. The lone exception was the loss of Indianapolis less than two weeks before the end of the war to a submarine in the Philippine Sea after she delivered the atomic bomb material to Tinian. There were no cruisers lost to aircraft bombs or torpedoes, or to the Japanese suicide bombers.

5.3 Wartime Design Evolution and Building Program

During the period before the war from 1924 through 1941 the U.S. Navy commissioned 33 cruisers, an average of 1.8 new cruisers per year. Eleven of these cruisers were commissioned in 1937 – 1939 (9 CLs & 2 CAs) as part of the Roosevelt Administration's WPA "make-work" projects. But, by 1940, with the war going badly in Europe, even this rate of production seemed inadequate. When Congress authorized a 70% expansion of the Navy (the Vinson-Trammel Act) there was a scramble to increase production of all types of warships. Accordingly, the Navy elected to make only those improvements that would not delay production, relying as much as possible on the existing designs which were considered satisfactory even if not optimum.

In 1942 eight CLs were commissioned and in 1943 seven more CLs and four CAs were commissioned. This building rate continued through the end of the war with 11 cruisers commissioned in 1944 and 18 in 1945. These cruisers were (mostly) divided into Cleveland class light cruisers (improved Brooklyns) and Baltimore class heavy cruisers (improved Wichitas). The General Board was not entirely happy with either design; as a result of Treaty limitations and technological changes, the Cleveland's were too slow compared to the Iowa class battleships and the Baltimores lacked protection against more recent 8-inch shells. These arguments were swept away by "mobilization production fever." Design activity continued, but could not be allowed to hamper production.

With the start of the war, all Treaty restrictions were no longer in force. The U.S. Navy designed two new cruisers, the Cleveland class light cruiser (CL) and the Baltimore class heavy Cruiser (CA). Cleveland was developed from the Brooklyn design, while Baltimore was based on the heavy cruiser Wichita, itself a Brooklyn derivative. The Cleveland Class had twelve 6-inch/47 in four triple turrets (2 forward, 2 aft) and twelve 5-inch/38 in twin mounts (one each on the center line fore and aft and two each on either side of the ship).

The Baltimore class was an enlarged Wichita. The Baltimore class had three triple 8-inch/55 turrets (two forward and one aft) and six twin - 5-inch/38 mounts (one each on the centerline fore and aft, and two on each side).

World War II saw a major increase in radar technology with new surface search, air search, and fire control radars being developed and installed on the cruisers throughout the war. The growth of radar and the air threat created a need to assimilate a growing amount of information, evaluate it quickly, and then respond to multiple targets. This led to the creation of Combat Information Centers (CIC) in combatants, which grew in the size and importance as technology proliferated. Earlier cruisers had to find space for CIC in their superstructure, but later cruisers (Fargo (improved Cleveland), Oregon City (improved Baltimore), and Juneau (improved Atlanta) classes) incorporated fully protected CICs inside the armored box.

As the war proceeded it became clear that the anti-aircraft capabilities of the cruisers had to be improved. This improvement generally involved removing the unreliable 1.1-inch rapid fire AA machine gun (which was complex and developed a poor reputation in service^xl) and replacing them with the foreign designed 40mm and 20mm AA guns, as well as adding as many 40mm and 20mm guns as could be fitted on the ship without over loading the hull. Additionally, open bridges were added to allow improved aircraft sight lines for directing the AAW efforts. Many of the cruisers were critically close to being overweight, so to compensate for the additional AAW guns being installed, items had to be removed, such as one of the two aircraft catapults, range finders from some of the turrets, and reducing the height of the masts. When the Japanese began using kamikaze tactics the need for heavier AA weapons became apparent. In addition to adding more AA weapons, multiple AA fire control directors were added. To improve the ability to engage crossing targets, AA guns (usually 40mm) were mounted in the bow and on the stern.

A cruiser hull also had the speed, endurance, and capacity to perform as a light carrier. Nine USN light cruisers (Cleveland class) were converted to CVL's (small aircraft carriers) while under construction. These 14,750 ton ships became the Independence class. While a small carrier was limited in how many aircraft it could support, the need for additional sea-based air platforms in WWII was very great. This use of cruiser hulls recalled conversions performed by the Royal Navy in the WWI era on the battle cruisers Courageous, Glorious and Furious. The US CVL's used the original cruiser machinery and basic hull, bulged to improve stability, but had all their armament and superstructures removed. A hangar deck and flight deck were added, with funnels trunked over to starboard and a small island. Top speed was 31.6 knots. Many of these ships served along with fleet carriers in Pacific task forces. After the war, they were quickly decommissioned because they were near their stability and volume limits at delivery.

However, a second, Saipan class of CVL's was also built, based on the Baltimore class heavy cruiser hull widened on paper prior to the start of construction. These 19,100 ton ships had much more growth potential and served as carriers or command ships into the 1970's.

5.4 New US Wartime Designs

In addition to cruiser types that had been in production prior to the war, additional types were introduced during the conflict. These were a specialized minelayer, the battle cruiser, new only to the US Navy, and the antiaircraft cruiser. Also, small aircraft carriers were built on cruiser hulls.

Many light cruisers were fitted with weather deck mine rails in order to dash into enemy coastal waters and lay down a disruptive string of mines. The mission was so highly thought of that the UK, after a conversion of an existing cruiser (the Adventure), built the six ships of A