Washington Naval Treaty

Guns from battleships being scrapped in Philadelphia Navy Yard in December 1923. USS South Carolina being dismantled in the background.

The Washington Naval Treaty, also known as the Five-Power Treaty, limited the naval armaments of its five signatories: the United States of America, the British Empire, the Empire of Japan, the French Third Republic, and the Kingdom of Italy. The treaty was agreed at the Washington Naval Conference, which was held in Washington, D.C. from November 1921 to February 1922, and was signed by representatives of the treaty nations on 6 February 1922. It was an attempt to prevent a naval arms race that began after World War I.

The terms of the treaty were modified by the London Naval Treaty of 1930 and the Second London Naval Treaty of 1936. By the time of the latter, Japan had declared it would no longer abide by the terms of the treaty and Italy was secretly disregarding it. Germany was never affected by the Washington or London treaties; its naval construction was limited under the Treaty of Versailles, the peace treaty that ended World War I.

Background

In the aftermath of World War I the British Empire had the world's largest and most powerful navy, followed closely by the United States and more distantly by Japan. All three embarked upon large programs of new capital ships (battleships and battlecruisers). In 1920, the United States had declared an aim to produce a navy "second to none", and had already laid down keels for five battleships and four battlecruisers. Japan was at the start of its 8:8 program (eight battleships and eight battlecruisers). In early 1921 the British finalized the design and ordered four very large battlecruisers (G3 battlecruiser) with plans for four matching battleships (N3 battleship) to follow. This burst of capital ship construction kindled fears of a new naval arms race, similar to the Anglo-German Dreadnought race leading up to World War I.

Terms

Tonnage limitations
Country	Capital ships	Aircraft carriers
British Empire	525,000 tons (533,000 tonnes)	135,000 tons (137,000 tonnes)
United States	525,000 tons (533,000 tonnes)	135,000 tons (137,000 tonnes)
Japan	315,000 tons (320,000 tonnes)	81,000 tons (82,000 tonnes)
France	175,000 tons (178,000 tonnes)	60,000 tons (61,000 tonnes)
Italy	175,000 tons (178,000 tonnes)	60,000 tons (61,000 tonnes)

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 to the values tabulated at right. In addition, no single ship could exceed 35,000 tons (35,560 t), and no ship could carry a gun in excess of 16 inches (406 mm).

The "standard tonnage" was defined in the treaty to exclude fuel (and boiler water) because the British argued that their global activities demanded higher fuel loads than other nations and they should not be penalized.

Aircraft carriers were addressed specifically by the treaty. In addition to total tonnage limits, rules regarding maximum vessel size were imposed. Only two carriers per nation could exceed 27,000 tons (27,400 t), and those two were limited to 33,000 tons (33,500 t) each - this exception was in fact made to allow the reuse as carriers of certain battlecruisers being built, and gave birth to the USS Lexington and the Akagi. The number of large guns carried by an aircraft carrier was sharply limited—it was not legal to put a small number of 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. For example, the United States could build on Hawaii and the Alaskan mainland, but not on the Aleutian Islands. The various navies of the British Empire — considered under the treaty as one entity — were treated similarly and the facilities of the Royal Australian Navy (which had to give up the battlecruiser HMAS Australia) and the New Zealand Division of the Royal Navy could be built up by their respective governments, but not the base of Hong Kong. Japan could build on the home islands, but not Formosa.

Treaty members were allowed to replace or build ships within the terms of the Treaty but any build or replacement had to be directly communicated to the other Treaty signatories.

On 29 December 1934, the Japanese government gave formal notice that it intended to terminate the treaty. Its provisions remained in force until the end of 1936, and it was not renewed.

Territorial Scope and Application

Article XIX of the treaty made numerous clarifications in regard to the territories possessed by the United States, the British Empire, and Japan, and agreed to maintain the status quo with regard to fortifications and naval bases. These territories were specified as:

(1) The insular possessions which the United States now holds or may hereafter acquire in the Pacific Ocean, except (a) those adjacent to the coast of the United States, Alaska and the Panama Canal Zone, not including the Aleutian Islands, and (b) the Hawaiian Islands;

(2) Hong Kong and the insular possessions which the British Empire now holds or may hereafter acquire in the Pacific Ocean, east of the meridian of 110° east longitude, except (a) those adjacent to the coast of Canada, (b) the Commonwealth of Australia and its Territories, and (c) New Zealand;

(3) The following insular territories and possessions of Japan in the Pacific Ocean, to wit: the Kurile Islands, the Bonin Islands, Amami-Oshima, the Loochoo Islands, Formosa and the Pescadores, and any insular territories or possessions in the Pacific Ocean which Japan may hereafter acquire.

Effects

In Europe, the Treaty changed planned building programs for most of the signatories. The British gave up their planned N3 battleships and G3 battlecruisers. Almost all of the forces built new designs in the new "heavy cruiser" class, but at the same time few new battleships were built. Instead, extensive conversions were made to existing battleships and battlecruisers, resulting in fleets in World War II that consisted primarily of ships laid-down before World War I. The United States built no new battleships until the keel of North Carolina was laid in October 1937 — a span of nearly 20 years.

A number of attempts were made to build new battleship designs within the Treaty limitations. The need to increase armor and firepower while keeping weight under the Washington limit resulted in experimental new designs like the British Nelson-class (based in part on the G3 design) and the French Richelieu.

In general, ship effectiveness is related to speed, armor and armament. Weight is related to ship length which permits higher speeds. Each nation used a different approach to circumvent the treaties. The US used high strength boilers for higher speeds in a smaller ship. Germany used high strength steels for better armor and lower weight (although this was in response to the Treaty of Versailles, not the Washington Naval Treaty). Britain designed ships that could have armor added after a war began, and in the case of HMS Rodney and HMS Nelson enhanced their armour by using boiler feed water tanks as part of the protective scheme. Italy simply lied about the tonnage of their ships. Japan withdrew from the treaty in 1936, and continued the building program that they had previously begun, to include placing 18.1 inch (460 mm) guns on battleship Yamato.

The majority of European nations were not concerned with military operations far from land, and therefore there was little interest in aircraft carrier construction. The Germans, French and Italians did not bother with aircraft carriers until World War II was clearly looming, at which point all of them started construction in small numbers. The Royal Navy, tasked with long-range operations the world over, clearly needed carriers and so continued construction. Between 1920 (prior to the treaty) and the start of World War II the British built six new carriers, all various one-off designs. The US had six carriers at the start of the war in 1939, not including the old CV-1, Langley, as she had been converted to a seaplane carrier (AV-3) in 1936 to allow for the completion of Wasp. After the Washington Treaty terminated, the US laid down six new carriers, starting with Hornet (a repeat Yorktown) and Essex (the first of a new class). Japan converted the incomplete battleship Kaga and battlecruiser Akagi to aircraft carriers to conform to the Washington Naval Treaty. These conversions provided much needed experience and helped to build future classes of aircraft carriers. Japan had ten carriers at the start of the war.

The French were not pleased with the treaty. They had argued that they should be allowed a larger fleet than Italy, since France had to maintain a fleet in both the Atlantic and the Mediterranean, but the Italians had to be concerned only with the Mediterranean. This would obviously imply that the Italian presence in the Mediterranean would be stronger than the French. Nevertheless, they signed the treaty, partially reassured by their alliance with the British.

The effects of the Treaty on the United States could not have been more different. The Treaty, coupled with the attack on Pearl Harbor on December 7, 1941 was a major cause of the United States Navy's conversion from a battleship fleet to a 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 vessels in order to comply. However, the only aircraft carrier in the US fleet before the treaty was signed was USS Langley (11,500 tons, 11,700 t), a converted collier. Not only did carriers have separate limits, but as an experimental vessel, Langley did not count against the tonnage restrictions. The US Navy thus had a free rein to build carriers.

In the 1920s the U.S. Department of the Navy had a low opinion of the concept of naval aviation despite (or perhaps because of) Billy Mitchell's 1921 success in using US Army Air Service bombers to sink the German battleship Ostfriesland. However, to comply with the treaty, two battlecruisers of the Lexington class still under construction, USS Lexington (43,500 tons, 44,200 t) and USS Saratoga(43,500 tons, 44,200 t), had to be disposed of. They were converted into carriers USS Lexington (33,000 tons, 33,500 t) and USS Saratoga (33,000 tons, 33,500 t), although that choice was only slightly preferred over scrapping. However they were also equipped with eight 8-inch guns, the maximum number of that caliber allowed by the treaty for aircraft carriers bigger than 27,000 tons. The treaty allowed these ships to displace 33,000 tons, and have an additional 3,000 tons added for deck and underwater protection; hence a final 36,000 ton standard displacement figure. They were subject to a great deal of creative accounting as to these figures, and both were far closer to 40,000 tons at the time they were commissioned.

In 1931, the United States was still well under the treaty's limit on carriers. USS Ranger (14,500 tons, 14,700 t) was the first US carrier designed as such — no other class of capital ship could be built — and the Navy began incorporating the lessons from those first four carriers into the design of two more. In 1933, Congress passed Franklin Roosevelt's "New Deal" package of legislation, which included nearly $40 million for the two new carriers: Yorktown (19,800 tons, 20,100 t) and Enterprise (19,800 tons, 20,100 t). Still bound by the 135,000 ton (137,000 t) limit, the keel of the final US pre-war Treaty carrier Wasp (14,700 tons, 14,900 t) was laid down on April 1, 1936. The US Carrier Fleet now totaled 135,000 tons (137,000 t), nominally, and there it remained until the treaty was terminated by Japan in 1936. As with their predecessors, the two Yorktowns and Wasp were subject to a great deal of creative accounting; their actual displacements were closer to 25,000 and 20,000 tons respectively. The actual carrier fleet displacement in 1936 was closer to 165,000 tons, the displacement of only two Forrestal-class supercarriers of just twenty years later.

The naval treaty had a profound effect on the Japanese, many of whom saw the 5:5:3 ratio of ships as another way of being snubbed by the West (in fact, the Japanese, having a one-ocean navy, had a far greater concentration of force than the two-ocean United States Navy or the three-ocean Royal Navy). It also contributed to a schism in high ranks of the Imperial Japanese Navy; on one hand were the Treaty Faction officers, and on the other were their opponents who were also allied to the ultranationalists in the Japanese army and other parts of the Japanese government. For Treaty Faction opponents, the Treaty was one of the factors which contributed to the deterioration of the relationship between the United States and the Japanese Empire. The unfairness, at least in the eyes of the Japanese, is also what led to Japan's renunciation of the Naval Limitation Treaties in 1936. Isoroku Yamamoto, who later masterminded the Pearl Harbor attack, held that Japan should remain in the treaty and was therefore regarded by many as a member of the Treaty Faction. His view was more complex, however, in that he felt the United States could out-produce Japan by a greater factor than the 5:3 ratio because of the huge US production advantage, on which he was expert, having served in the Japanese Embassy in Washington. He felt that other methods would be needed to even the odds, which may have contributed to his advocacy of the plan to attack Pearl Harbor. However, he did not have sufficient influence at Navy headquarters nor in the government, and Japan left the treaty in 1936.

Cryptanalytic influences on the treaty

What was unknown to the participants in the Conference was that the American Black Chamber in New York City, under Herbert Yardley, was spying on the delegations' communications to and from their home capitals. In particular, Japanese communications were thoroughly penetrated, and American negotiators were able to get the minimum possible deal the Japanese had indicated they would accept, and below which they would leave the Conference. As this ratio value was unpopular with much of the Imperial Japanese Navy, and with the increasingly active and important ultranationalist groups, the value the Japanese Government accepted was the cause of much suspicion and accusation among Japanese between politicians and Naval officers.

See also

• Washington Naval Conference

External links

• Conference on the Limitation of Armament Full text of the Washington Naval Treaty.