Japanese entry into WW1 began with the Anglo Japanese Alliance of 1902. Although the cornerstone of this agreement, and its primary purpose, was mutual recognition of interests of the parties in China, an obscure provision was the promise of support if either signatory became involved in war with more than one Power. This clause was triggered when the British declared war on Austria-Hungary on August 12th, 1914, having previously declared war on Germany on August 4th. Accordingly, Japan declared war on both on August 23rd.
Why did Japan want to become involved in WW1? They had little interest in the events unfolding in Europe, except that a prolonged conflict would certainly distract the European powers from their interests in China and weaken their position there by requiring the transfer of ships and soldiers.
However, the Japanese saw an opportunity to enhance their standing in the region by supplanting Germany and to take another step towards recognition of Japan as a world power.
What were the Japanese contributions to the Allied effort in WW1?
- The capture of the German concession at Tsingtao (Qingdao) in northern China. The Japanese led the attacking force which consisted of 23,000 Japanese and 1,500 British and Indian troops taken from the Hong Kong garrison. After an eight day battle, the mostly German garrison ran short of ammunition and surrendered. Japanese losses were 733 killed and 1,282 wounded, plus the cruiser Takachiho and the destroyer Shirotaye were sunk.
- The capture of the German Pacific colonies north of the equator, the Mariana (except Guam), Marshall and Caroline Islands, which wasn’t a dangerous task as none of the islands had a military garrison.
- The Japanese Navy secured the sea lanes in the Western Pacific and Indian Oceans, not much of a challenge after the Germans withdrew their East Asiatic Squadron in September 1914 and the Indian Ocean raider SMS Emden was destroyed by the Australians in November 1914.
- The British allowed the Japanese to base ships at Singapore, which proved of great value to the British in late January 1915 when Muslim soldiers from the Indian Army, responding to the Ottoman Jihad declaration, mutinied and rampaged freely in the city for two days until an ad hoc force headed by 158 Japanese Marines restored order.
- At the end of 1916 the British asked for Japanese naval assistance in the Mediterranean. A squadron of 3 cruisers and 14 destroyers was dispatched and took over all anti-submarine escort and search duty in the sea lane between Suez and Malta. One destroyer, the Sakaki, was torpedoed by the Austro-Hungarian U-27. Fifty nine sailors died and the ship was never returned to service.
- In July 1918 Japan agreed to contribute 12,000 soldiers as part of the Siberian Expeditionary Force, which included nearly 8,000 Americans, to secure, protect and operate the Trans-Siberian Railroad. The Japanese occupied Vladivostok and their soldiers ventured as far into Russia as Lake Baikal. The Japanese stayed until the fall of 1920, losing about 5,000 men, mostly to disease and bad conditions.
A footnote for the aviation history buffs: two ‘firsts’ happened at Tsingtao. The Japanese seaplane carrier Wakamiya launched the first naval air raids in history, and second, one of these Farman MF-7 seaplanes was the first aircraft in history to be shot down by another aircraft, hit by a Mauser C-96 automatic pistol fired by the pilot of a Taube reconnaissance plane.
For their participation, Japan was accorded full recognition as a combatant by the Allies, with voting power at the peace conference equal to each of the Western Front powers. Japan also got four years of freedom to pursue aggression against China without European objection.
What did Japan want to gain from the peace? Permanent recognition of their annexation of German territories already occupied and a declaration of racial equality.
At the conference, the Japanese delegation proposed an amendment after Article 21 of the Covenant of the League of Nations, Part I of the Versailles Treaty, by adding this provision.
The equality of nations being a basic principle of the League of Nations, the High Contracting Parties agree to accord as soon as possible to all alien nationals of states, members of the League, equal and just treatment in every respect making no distinction, either in law or in fact, on account of their race or nationality.
On April 11th, 1919 this amendment was carried by a vote of 11 to 8. However, U.S. President Woodrow Wilson, who was the chairman, ruled that, due to the strongly-voiced objections by British Commonwealth, Belgian, Portuguese and even American interests, approval required unanimity. All compromise negotiations failed; the amendment was defeated.
Japan didn’t get permanent sovereignty over the captured territories, either. Instead, the League of Nations granted Japan a Class C Mandate, which recognized that the lands would be “best administered under the laws of Japan as an integral part of Japanese territory”, and so they were until Japan’s defeat in WW2.