Washington Naval Treaty
US Secretary of State Charles Evans Hughes opened the Washington Naval Conference on the 21st of November 1921 with a bold declaration. He stated clearly that the way to disarm was simply to disarm. His slogan received enthusiastic public endorsement and helped abbreviate the conference proceedings. Hughes proposed a ten-year pause on capital ship construction including all existing building projects. He demanded scrapping of ships to establish a tonnage ratio of five to five to three point six seven to one point six seven between Britain, the United States, Japan, France, and Italy respectively. British delegates accepted these proposals despite domestic outrage over their inability to maintain fleets simultaneously in the North Sea, Mediterranean, and Far East. The Japanese delegation faced internal division regarding the terms. Katō Tomosaburō led the delegation and preferred accepting the limits to avoid an economic crisis from an arms race. He noted Japan possessed only fifty-five percent of American capital ships and eighteen percent of US GDP at the start. Katō Kanji opposed this view as president of the Naval Staff College. He argued for thorough preparation against an inevitable conflict with superior American industrial might. French representatives initially rejected reducing their capital ship tonnage to one hundred seventy-five thousand tons. They demanded three hundred fifty thousand tons instead. Concessions on cruisers and submarines eventually persuaded them to agree. Italian demands for parity were accepted under pressure from American and British delegations.
The treaty established specific quantitative restrictions on naval vessels signed by the 6th of February 1922. Capital ships including battleships and battlecruisers were limited to thirty-five thousand tons standard displacement. Guns could not exceed sixteen-inch caliber. Aircraft carriers were restricted to twenty-seven thousand tons carrying no more than ten heavy guns of eight-inch caliber maximum. Signatories could use two existing capital ship hulls for aircraft carriers with a limit of thirty-three thousand tons each. All other warships including cruisers and destroyers faced a maximum displacement of ten thousand tons. The tonnage limits defined Articles IV and VII creating a strength ratio of approximately five to five to three point seven five to one point seven five. Britain and the United States received five hundred twenty-five thousand tons of capital ships. Japan received three hundred fifteen thousand tons. France and Italy each received one hundred seventy-five thousand tons. The United States had to scrap thirty existing or planned capital ships while Britain scrapped twenty-three and Japan seventeen. Chapter II detailed individual ships retained by each navy allowing the US to complete two Colorado class ships. Britain completed two new Nelson class ships in accordance with treaty limits. Ships rendered ineffective for military use could be sunk, scrapped, or converted into target ships if all combat parts were removed.
Several powers exploited technical definitions to build larger ships or bypass displacement caps during the interwar period. The Japanese light aircraft carrier Ryūjō attempted to exploit the definition requiring vessels over ten thousand tons. It was built under that threshold but proved too small to function fully before being expanded later. American conversions of Lexington and Saratoga from battlecruisers to carriers exceeded their original thirty-three thousand ton limit. The US argued they were reconstructing these ships to add anti-aircraft defenses adding an extra three thousand tons. British Nelson class ships utilized a loophole regarding fuel and reserve boiler feed water. By making liquid layers within torpedo defense systems usable as boiler feed water, this weight did not count toward displacement limits. This allowed stronger defenses than otherwise practical. France violated the treaty by laying down battleships in 1935. Combined with two other ships under construction, total tonnage exceeded the seventy-thousand-ton limit on new French battleships. Italy repeatedly violated individual ship displacement limits while attempting to stay within cruiser constraints. By the late 1920s it abandoned pretense and built ships topping twenty-seven thousand tons. Italian submarines of the mid-1930s displaced well beyond one hundred thousand tons yet misrepresented their size.
The naval treaty profoundly affected Japanese strategic thinking and internal politics. With superior American industrial power, a long war would likely end in defeat for Japan. Gaining strategic parity was economically impossible according to many observers. Many Japanese viewed the five-to-five-to-three ratio as another snub by Western powers. Terms contributed to controversy between Treaty Faction officers and Fleet Faction opponents within the Imperial Japanese Navy. The Fleet Faction allied with ultranationalists in the army and government. Some argued the treaty prompted Japanese expansionism in the early 1930s due to perceived unfairness. Isoroku Yamamoto later masterminded the attack on Pearl Harbor but held complex views on the treaty. He believed the United States could outproduce Japan far more than the five-to-three ratio suggested. Having served at the Japanese embassy in Washington he knew about Detroit auto factories and Texas oil fields. Chūichi Nagumo argued against remaining in the treaty while Yamamoto favored staying. On the 29th of December 1934, the Japanese government gave formal notice intending to terminate the agreement. Provisions remained in force until the end of 1936 and were not renewed.
American cryptographic interception significantly influenced the final terms reached during negotiations. The Black Chamber or Cypher Bureau commanded by Herbert Yardley spied on delegations communications with their home capitals. Japanese communications were deciphered thoroughly allowing American negotiators to extract the absolute minimum possible deal from Tokyo. This intelligence advantage enabled the US to secure terms that represented the lowest acceptable level for Japan. The value accepted by the Japanese government caused much suspicion among politicians and naval officers back home. Many within the Imperial Japanese Navy viewed the outcome as a betrayal despite its strategic necessity. The revelation of this espionage added layers of distrust between allies who had just agreed to limit their navies. It remains unknown how many other details were intercepted beyond what was publicly documented. The impact on the final agreement terms cannot be overstated given the precision of the American position.
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Common questions
What was the Washington Naval Treaty signed on?
The Washington Naval Treaty was signed by signatories on the 6th of February 1922. This agreement established specific quantitative restrictions on naval vessels including battleships and battlecruisers.
Who opened the Washington Naval Conference in November 1921?
US Secretary of State Charles Evans Hughes opened the Washington Naval Conference on the 21st of November 1921 with a bold declaration to disarm. He proposed a ten-year pause on capital ship construction and demanded scrapping of ships to establish tonnage ratios between major powers.
How many capital ships did Japan receive under the Washington Naval Treaty limits?
Japan received three hundred fifteen thousand tons of capital ships under the Washington Naval Treaty limits. The treaty required Japan to scrap seventeen existing or planned capital ships while maintaining this specific tonnage allowance compared to Britain and the United States.
When did the Japanese government give formal notice intending to terminate the Washington Naval Treaty?
The Japanese government gave formal notice intending to terminate the agreement on the 29th of December 1934. Provisions remained in force until the end of 1936 and were not renewed after that date.
Which American agency deciphered Japanese communications during the Washington Naval Conference negotiations?
American cryptographic interception significantly influenced final terms through the Black Chamber or Cypher Bureau commanded by Herbert Yardley. This unit spied on delegations communications with their home capitals allowing negotiators to extract the absolute minimum possible deal from Tokyo.