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Naval Disarmament Treaties


Photograph of delegates to Washington Conference

Delegates to the Washington Conference.

National Archives. Via ibiblio.org

The Washington Treaty of 1922. Following the First World War, a naval arms race began warming up between the United States, Britain, and Japan. To avoid the enormous cost of this race, and to limit the size of battleships to what the U.S. Navy could move through the Panama Canal, the United States invited the other major naval powers to a disarmament conference in Washington in 1922.  The U.S. Secretary of State shocked the delegates by offering to scrap a large fraction of new U.S. battleship construction in return for an agreement on naval arms limitations. 

The resulting Washington Naval Treaty limited both the design and numbers of battleships of the major powers, with the United States and Britain limited to 15 battleships, Japan to 10, and Italy and France to 5 each. All powers were limited to battleships of not more than 35,000 tons displacement with guns limited to 16" (406mm) caliber.  Carriers were also limited in size and total tonnage. New battleships could not be constructed except to replace older battleships that had reached twenty years' age, and modernization of older battleships and carriers could not increase their displacement by more than 3000 tons nor increase the caliber of their main batteries. Cruisers were limited to 10,000 tons displacement and 8" (203mm) caliber guns. However, a proposal by Britain to outlaw submarines entirely was rejected by the other powers, especially Japan, whose submarine fleet was expected to play a major part in wearing down the U.S. Fleet as it crossed the Pacific to relieve the Philippines in any future war. 

The tonnage limits of the Washington Treaty were expressed in terms of standard tonnage, defined in the Treaty as the displacement when fully manned and loaded for combat, but excluding fuel oil and reserve feedwater. The exclusion of fuel and feedwater was a concession to Britain and the United States, whose navies required long endurance for operations far from bases. This replaced normal displacement as a measure of warship tonnage, which was defined as displacement fully manned and equipped and with two-thirds of maximum ammunition and other consumable stores.

The Washington Conference also restricted new or improved fortifications in the Pacific to the main territories of the treating powers. Japan could fortify its home islands, the British could fortify Singapore, and the United States could fortify Hawaii and Alaska, but Japan could not fortify the Kuriles or Formosa and the Unites States could not fortify Guam or the Aleutians or further fortify the Philippines. The treaty also superseded Japan's naval alliance with Britain, which had the effect of allowing Britain and the United States to more closely align their foreign policies.

The Washington Treaty halted construction of the U.S. Navy's 1920 South Dakota class (not to be confused with the second South Dakota class whose units were completed during the Pacific War.) The signatory powers agreed that Japan could retain its two Nagato class battleships and Britain could complete two Nelson class battleships in return for the United States retaining all three of its Colorado class battleships that had already been completed. Both Japan and the United States were permitted to convert two battle cruiser hulls each into aircraft carriers.

Text of the Washington Treaty of 1922

The Geneva Conference of 1927. Although the Washington Treaty had restricted the displacement and armament of cruisers, it had not limited their numbers or aggregate tonnage. Following the Washington conference, the Japanese began a massive program of construction of powerful cruisers. This threatened to renew the naval arms race, and so the Americans proposed the adoption of a limit on total tonnage of cruisers that left the design limits for individual ships unchanged. The British, with a far-flung maritime empire to patrol, proposed almost exactly the opposite, calling for severe reductions on the permitted design specifications for individual ships, but with a very generous limit on total tonnage. This would permit the British to build a large fleet of light cruisers.

The British proposal would also have given them a considerable advantage relative to the Americans, because their extensive system of bases would allow small cruisers with relatively limited endurance to project power more effectively than the Americans.

While the United States had been able to negotiate from a position of strength at Washington, because of its massive building program for battleships, the American negotiators enjoyed no such advantage at Geneva. American construction of cruisers had been "anemic" (Kuehn 2008) and left the U.S. negotiating from a position of weakness. The disagreement between the United States and Britain wrecked the Geneva Conference, and the powers deferred the question of new limitations until the 1930 London conference.

The London Treaty of 1930. In 1930, a third conference in London brought together Britain, the United States, and Japan.  This treaty established further limits on lighter classes of ships, including cruisers, destroyers, and submarines. 

The treaty limited total tonnage of cruisers to 339,000 tons for Great Britain, 323,500 tons for the United States, and 208,850 tons for Japan. The total number of heavy cruisers was also limited, to 18 for America, 15 for Great Britain, and 12 for Japan. The chief effect of the cruiser limitations was to cause Britain and the United States to shift their emphasis to light cruiser construction.

Destroyer tonnage was limited to 1500 standard tons per unit, except that 16% of the destroyer units of each could be flotilla leaders of up to 1850 standard tons. All were limited to 5" (127mm) guns. Britain and the United States could build to 150,000 total tons and Japan to 105,000 total tons, a ratio of 7:10. This was an increase from the 6:10 ratio for battleships from the Washington treaty but did not satisfy the Imperial Navy's Fleet Faction.

Submarines were limited to 2000 tons surface displacement and guns of not more than 5.25" (130mm), though torpedo size and numbers was oddly left unrestricted. The number of coastal submarines (defined as those displacing less than 600 tons) was unlimited, but oceangoing submarines (those from 600 to 2000 tons displacement) were limited to a total of 52,700 tons per power. The submarine limitation was particularly resented in Japan (quoted by Carpenter and Polmar 1986):

The Naval General Staff in Tokyo was enraged at this. Equality of submarine tonnage was totally unsatisfactory. Japan's war games had show that she needed an absolute minimum of 78,000 tons. A strength of 52,700 tons would leave her short by two squadrons of submarines — sixteen boats — of what her planners considered necessary to the strategy of attrition. The results of the London Conference were thus looked upon as having placed Japan's national defense in jeopardy.

Ships of less than 2000 tons standard displacement; with guns of not more than 6.1" (150 mm) caliber, and with not more than four guns of greater than 3" (75mm) caliber; and which had a maximum speed not in excess of 20 knots were exempt from the destroyer restrictions. The British, who had originally proposed this exempt class, used the exemption to construct antisubmarine sloops for convoy escort, while the Americans used the exemption to construct gunboats of the Erie class.

Continuing resentment at the naval disarmament treaty structure led Japan to denounce the treaties in December 1934.

Text of the London Treaty of 1930

The London Treaty of 1936. A further conference in London in 1935-1936 was desultory, since Japan had already announced its withdrawal from the limitations system.  The participating powers (U.S., Britain, and France) agreed to continue limiting displacement to 35,000 tons and to reduce maximum gun caliber to 14" (356mm). However, the treaty stipulated that the maximum gun caliber would revert to 16" if Japan did not ratify the treaty within a year, and maximum displacement would increase to 45,000 tons if any navy built a ship exceeding the 35,000 ton limit. Japan failed to ratify the treaty, and the major powers promptly began building up their navies.  However, the first U.S. and Japanese battleships built during this new arms race did not commission until late 1941.  The British were a little faster off the mark, commissioning their first new battleships in 1940, but at the cost of building these battleships with 14" rather than 16" guns.

The legacy of the naval disarmament treaties is difficult to interpret.  The signatory powers abode by the terms of the treaties in reasonably good faith until the collapse of the treaty system in 1935, largely because this was in everyone's interest. The treaties prevented "a naval race no one really wanted" (Friedman 1985) between Britain and the United States at a time when the foreign interests of these two nations were becoming increasingly aligned.  Although the United States clearly had the means to win a naval arms race, the cost would have been ruinous.  On the other hand, resentment of the terms of the disarmament treaties was widespread in Japan and contributed to the rise of ultranationalism, and the restrictions on American fortifications in the Pacific left the Philippines and Guam dangerously vulnerable. On balance, the treaties benefit Japan, leaving her with naval supremacy in the Far East and making any execution of Plan ORANGE far more chancy, while simultaneously leaving the Japanese feeling humiliated and resentful — a dangerous combination.

The treaties proved a particular point of contention within the Japanese Navy. The principal Japanese naval representative at the conference, Kato Tomosaburo, believed that the Japanese Navy was a deterrent against any American aggression, not a force preparing for inevitable war, and believed that it was folly for Japan to try to match the United States in an arms race. However, Kato Kanji, who was appointed as naval aide to the elder Kato at the conference, was a militantly nationalist proponent of building the largest fleet possible.

Curiously, public opinion in the United States tended to view the naval disarmament treaties as evidence that tensions had already been reduced in the Pacific, rather than as a means to reducing tensions. As a result, the United States did not even build up its light forces to the treaty limits. The Japanese saw things rather differently, and began an intensive program of construction of light forces. 

The cruiser displacement limit of 10,000 tons proved a particularly onerous limitation on ship design, and while no treaty power designed ships from the outset that violated the limit, most ended up with overweight ships. This was particularly true of the Japanese, who were thousands of tons over weight when the other powers were hundreds of tons over weight, and it became more true as Japan prepared to withdraw from the disarmament treaties. Evans and Peattie (1997) believe that the Japanese designers lacked the experience to achieve precisely the design displacement, but they also believe that the Navy General Staff made demands for additional weapons systems that they knew would push the designs over the limit.

Text of the London Treaty of 1936

References

Bagnasco (1977)

Carpenter and Polmar (1986)

Drea (2009)

Evans and Peattie (1997)

Friedman (1984, 1985)
Garzke and Dullin (1985)

Kuehn (2008)

Osborne (2005)
Spector (1985)

U.S. Department of State (accessed 2013-12-27)

Willmott (1982)



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