Washington Naval Treaty

Washington Naval Treaty. The Washington Naval Treaty, formally the Five-Power Treaty, was a landmark international arms limitation agreement signed in 1922. It aimed to prevent a costly naval arms race among the victors of World War I by imposing strict limits on capital ship and aircraft carrier tonnage. The treaty established a fixed ratio of naval strength between the five major powers and introduced a ten-year construction "holiday" for new battleships, fundamentally reshaping global naval strategy in the interwar period.

Background and context

The immediate catalyst for the conference was the intense naval rivalry, particularly between the United States and the British navies, which had accelerated after the Paris Peace Conference. The ambitious naval construction programs of the United States, including the planned South Dakota-class, and Japan's Eight-eight fleet plan, threatened to ignite a financially ruinous arms race. This occurred amidst a global climate shaped by the devastation of World War I, the high costs of the Anglo-German naval arms race, and a growing pacifist and isolationist sentiment in Western democracies. The administration of Warren G. Harding, with Secretary of State Charles Evans Hughes taking a leading role, invited the other major naval powers to the Washington Naval Conference to negotiate a comprehensive settlement.

Key provisions and limitations

The treaty's core was a system of tonnage ratios for capital ships—battleships and battlecruisers—set at 5:5:3:1.75:1.75 for the United States, the British Empire, the Empire of Japan, France, and the Kingdom of Italy respectively. It imposed a total tonnage cap and restricted individual battleship displacement to 35,000 tons with guns no larger than 16 inches. A separate category was created for aircraft carriers, also with individual tonnage limits and gun caliber restrictions. Significantly, the treaty mandated a ten-year moratorium on the construction of new capital ships and required the scrapping of numerous existing or building vessels, such as the American Lexington-class battlecruisers and the Japanese Tosa-class. It also included important clauses, negotiated by Elihu Root, restricting the fortification of naval bases in the Pacific Ocean, particularly affecting U.S. holdings like Guam and the Philippines.

Signatories and ratification

The principal signatories were the five major naval powers: the United States, the British Empire (representing the entire British Commonwealth), the French Third Republic, the Kingdom of Italy, and the Empire of Japan. The treaty was signed on 6 February 1922, in Washington, D.C., following months of negotiation at the Washington Naval Conference. Ratification processes proceeded in each nation, though not without debate; in Japan, the 5:5:3 ratio was controversially seen as a symbol of inferior status, fueling opposition from factions within the Imperial Japanese Navy General Staff. The treaty formally entered into force on 17 August 1923, after all parties had deposited their instruments of ratification. Related agreements signed at the same conference included the Four-Power Treaty and the Nine-Power Treaty, which addressed Pacific security and Chinese territorial integrity.

Effects and strategic impact

The treaty immediately halted the construction of dozens of capital ships and led to the scrapping or conversion of others, such as the American USS *Lexington* and USS *Saratoga* into aircraft carriers. It effectively cemented Anglo-American naval parity and legally constrained Japan to a secondary naval position, a source of lasting resentment. Strategically, it shifted naval competition into categories less restricted by the treaty, notably cruiser construction and naval aviation, leading to new classes like the County-class cruiser. The fortification restrictions created a strategic imbalance in the Pacific, influencing later war plans like the United States' War Plan Orange and Japan's Southern Operation. The treaty also had a significant economic impact, freeing government resources in the Roaring Twenties but also disrupting shipbuilding industries in nations like the United Kingdom.

Subsequent developments and end of the treaty

The treaty's limitations were first tested and extended by the London Naval Treaty of 1930, which attempted to regulate cruiser, destroyer, and submarine tonnage. However, rising international tensions and the expansionist policies of Italy and Japan undermined the system. Japan's demand for parity was rejected at the Second London Naval Conference in 1935, leading to its formal notice of withdrawal in 1934. The treaty officially expired on 31 December 1936, though Japan had already begun clandestine construction of vessels like the *Yamato*-class super-battleships that vastly exceeded treaty limits. The collapse of the agreement precipitated a full-scale naval arms race in the late 1930s, a direct precursor to the naval conflicts of World War II, including the Battle of the Coral Sea and the Battle of Midway.

Category:1922 treaties Category:Naval history Category:Arms control treaties Category:Interwar period treaties