Between the Wars: The London Treaty of 1930 Quiz

Answer: The Geneva Conference (1927)

The Washington Treaty of 1922 contemplated a further conference as the tenth anniversary of that Treaty approached. In 1927, U.S. President Calvin Collidge duly issued invitations to the four other signatory powers - Britain, Japan, France and Italy - to meet in Geneva. Britain and Japan accepted, but both France and Italy declined to attend.

The U.S. had two basic aims in Geneva: (1) limit the total tonnage of cruisers and smaller craft to 300,000 tons each for the U.S. and Britain and 180,000 tons for Japan and (2) avoid more severe restrictions on the size of individual warships.

The British delegation sought over 500,000 tons of cruisers and smaller ships, and a reduction in the maximum size of individual cruisers. Japan was also unwilling to limit its cruiser tonnage to only 60% of the total allowed to the U.S. and Britain.

The absence of France and Italy made little difference. The three largest naval powers could not even agree among themselves, and the Geneva Conference collapsed.

In 1930 - during the Depression - the same issues arose at the London Conference, but agreement was achieved.

Answer: Submarines

In 1921-1922, France refused to limit submarine construction because it sought a naval weapon to counter the Anglo-American superiority in capital ships. Thereafter, France launched a 2,800 ton submarine armed with 8" guns - but the "submarine cruiser" Surcouf was not successful. By 1930, a displacement of 2,000 tons and a maximum gun caliber of 5.1 inches were regarded as sufficient - but the parties were allowed to retain existing submarines that exceeded these limits.

The London Treaty gave Japan parity with the U.S. and Britain in the total tonnage of submarines, at 52,700 tons each.

Answer: Lowering the maximum cruiser gun caliber to 6.1"

The infamous "Treaty Cruisers" of the 1920s were an unfortunate result of the Washington Treaty. The 1922 pact defined a "capital ship" as a vessel armed primarily with guns that was either over 10,000 displacement and/or carried a gun larger than 8". By negative implication, the signatories could build an umlimited number of ships below those thresholds - and they built dozens of heavily gunned and poorly armored cruisers. By 1930, the major powers realized that a balanced 8" cruiser design could not be achieved in a 10,000 ton ship.

The London Treaty allowed the existing "Treaty Cruisers" to remain, but reduced the maximum gun size for new cruisers to 6.1". This allowed for more balanced designs: ships carrying 6" guns and also (mostly) protected against 6" shellfire.

The London Treaty also imposed limits on the total tonnage of cruisers and smaller vessels.

Answer: Protecting the crews of merchant ships

Article 22 of the London Treaty generally subjected submarines to "the rules of international law" governing surface ship attacks on merchant ships - but what were those rules? The United States had refused to agree to several prior treaties limiting commerce warfare, dating back to the mid-19th century. To clarify, Section 2 of Article 22 stated in part: "In particular, except in the case of persistent refusal to stop on being duly summoned, or of active resistance to visit or search, a warship, whether surface vessel or submarine, may not sink or render incapable of navigation a merchant vessel without having first placed passengers, crew and ship's papers in a place of safety." The signatory powers largely ignored these rules during World War II - as did Germany and the Soviet Union, which did not sign the Treaty.

Answer: "in excess of 10,000 tons "

The Washington Treaty allowed virtually unlimited construction of warships under 10,000 tons. In theory, the signatory powers could have built vast numbers of small carriers - though none were actually constructed. The London Treaty prevented this unused subterfuge.

The London Treaty did allow a cruiser or smaller vessel to have a flight deck provided the ship was "not designed or adapted exclusively as an aircraft carrier". The five powers didn't build any "flight deck cruisers" either - though they could have.

Answer: Yes - Japan, during World War Two

During the 1920s, there were speculative designs for "battleship-carriers" - which were allowed under the London Treaty as "capital ships" - but none were actually laid down.

The only true battleship-carriers were wartime expedients, long after the Treaty system collapsed. After losing its four largest aircraft carriers during the Battle of Midway in 1942, the Japanese Navy considered converting all of its capital ships (except the new Yamato and Musashi) into full flight-deck aircraft carriers. That plan was abandoned because of lack of resources. Instead, the ageing battleships Ise and Hyuga were converted into hybrid battleship-carriers, with flight decks replacing the after two main battery turrets. The hybrids were unsuccessful. The Japanese Navy also completed the Shinano, the third giant Yamato-class battleship, as an aircraft carrier, but she was not "in existence" in 1930.

Answer: Armor

The London Treaty limited cruisers to a maximum of 10,000 tons and 6.1" guns, so disclosing those characteristics should have confirmed the ship's compliance with the Treaty - if the information was accurate. Armor was not limited by the Treaty, but it was a key element in the displacement of cruisers.

The Italian and Japanese navies often exceeded the 10,000 ton displacement limit, but it was difficult or impossible to tell without knowing how much armor their cruisers carried. Japan also evaded the Treaty's limit on cruiser gun size (without breaking it) by arming new cruisers with 6" guns but designing them for quick conversion to carry 8" guns.

After withdrawing from the Treaty system, several Japanese cruisers were re-fitted with twin 8" turrets in place of their triple 6" turrets.

Answer: Torpedoes

The London Treaty did not limit the size, range or number of torpedoes or torpedo tubes carried by destroyers. This was strange because the torpedo was by far the destroyer's most powerful offensive armament. Beginning in 1928, Japan developed the 610 mm "Type 93" torpedo for surface ships. (After World War Two, American historian Samuel Eliot Morison dubbed it the "Long Lance"; the Japanese Navy didn't use that nickname.) Its secret was the use of compressed oxygen in the combustion process instead of compressed air.

The Type 93 had a maximum speed of 52 knots and a maximum range of over 40,000 yards. It could be fired against targets from beyond the visual horizon (usually 24,000 yds. on a clear day). The U.S. and Britain gave far less attention to the development of torpedoes during the 1920s and 1930s.

The American stardard surface-launched torpedo of World War Two had a range of about 12,000 yards and a much lower top speed.

Answer: Still had not built their quota from the 1920s

Government finances played an important role in bringing the powers to the conference table in 1922, and again during the Great Depression in 1930. Under the Washington Treaty, Italy and France were permitted to build one new capital ship each in 1927 and 1929. Neither could afford to do so, although their existing capital ships were obsolete. (Smaller and cheaper ships were considered but rejected.) Economic conditions in 1930 were even worse. France did not begin building a new capital ship until 1932.

Italy did not do so until 1934. The new ships entered service well after the Treaty system had collapsed.

Answer: Yes - only Japan

The Japanese Navy commissioned the battleship Yamato on December 16, 1941. She and her sister ship Musashi were by far the largest battleships ever built, at over 65,000 tons standard displacement and mounting 18" guns. Japanese strategists reasoned that the size of U.S. battleships would be limited by the Panama Canal.

They calculated that the largest gun the U.S. would deploy given that constraint would be 16", and planned the Yamato class to be individually superior to its projected American counterparts. Did they succeed? The U.S. Navy never developed a gun larger than 16" and the largest U.S. battleships to be completed could still pass through the Canal.

However, the U.S. Navy also developed a "super heavy" 16" shell with almost the same destructive effect as the Japanese 18" shell.

The comparisons are still debated today - and they are moot. The Yamato and Musashi never engaged U.S. battleships.