The Role of Japan in World War I

Fighting in the Far East represented just a small part of the experience of the Great War, but like the other theaters of war, it carried powerful consequences in the long term. Perhaps the most significant consequences in the Far East stem from the involvement of the Empire of Japan, which joined the Allied cause in August 1914. Japanese contributions to the war effort were limited, but effective.

In a time when most of the countries of the Far East, including China, were the subjects of colonial activity, Japan made itself a colonial power. The nineteenth-century visit from the American fleet showed Japan that it could no longer afford to remain aloof from the outside world. The country dedicated itself to the task of modernizing its society and increasing its international power, and nothing demonstrated its success like the stunning defeat Japan inflicted on Russia in 1905. This was not, however, the first acknowledgment of the growth of Japanese power; in 1902, Great Britain concluded an alliance with Japan to guarantee support against possible Russian aggression.

Subsequent diplomacy removed the threat of a Russian attack on British holdings, but Japan proceeded with a war against Russia on its own behalf. The effort earned the Japanese high respect in the rest of the world for the quality of their military, especially their navy, as well as the foundations of an empire of their own. They had already controlled the Korean peninsula; after the war with Russia, they added to this the territory of Manchuria. The Japanese were keen to extend this empire.

The arrival of World War I offered the prospect of doing so. War with Germany offered the prospect of modest reward with minimal risk. Siding with the Allies meant cordial relations with all of Japan’s immediate neighbors, including the other colonial powers. The Germans had a notable concession in China (Kiaochow Province) and a number of Pacific islands, and Japan hoped to benefit from the availability of poorly-guarded territory. The western powers, including the neutral United States, were unhappy at the prospect of seeing Japan gain too much, but Britain felt constrained by circumstances to accept that risk. Most importantly, the balance of naval power in the Far East was too close for Britain’s comfort. German naval strength was too near Britain’s own strength, and the support of a powerful navy was quite desirable.

Specifically, Britain cultivated Japanese intervention over Germany’s presence in China. The city of Tsingtao, which dominated Kiaochow, housed the China Squadron of the German Navy under Admiral von Spee. Demanding that Germany abandon this base and leave it to the Japanese offered the prospect of freeing the area from a German naval menace while avoiding a confrontation with China. Germany refused, and Japan declared war on August 23. A joint British-Japanese attack on Tsingtao followed in September, leading to the German capitulation in November.

After this, Japan was no longer involved in ground combat, although the army did seize German holdings in the Mariana, Caroline and Marshall Islands unopposed. Furthermore, one division did assist the Allies in 1918 when they intervened in the Russian Civil War. The bulk of Japanese involvement in World War I, however, played out in the naval arena.

The Imperial Japanese Navy (IJN) was already modern and experienced when the war began. It already included seven battleships of the dreadnought design, and three more were built during the war. Two more battleships preceded the adoption of the dreadnought concept, but were similar enough to dreadnoughts in their abilities to be classed with the dreadnoughts. The IJN also possessed eight battlecruisers and six modern cruisers, supplemented by a host of smaller or outdated craft. The Allies cooperated substantially in filling out each other’s navies; the Japanese possessed some destroyers that had been built by the British, and during the course of the war, they built twelve destroyers on behalf of the French Navy.

The Japanese participated in a number of joint naval efforts. One major example of this is the Allied response to Admiral von Spee’s breakout from China. With Spee’s squadron loose in the Pacific, Allied navies needed to spread out to cover a wide range of threats, and Japanese vessels were included. Sometimes they operated in task forces of their own, such as the squadron that was dispatched to Suva, but in other cases, they acted in a joint force. Interestingly, two Japanese vessels joined two British vessels in covering the waters around California.

Even after the death of Spee and the destruction of his squadron, Japan would remain active in the hunt for German raiders in the Pacific. More surprisingly, Japan played a role in naval operations in the Mediterranean, as well. Japanese destroyers contributed to convoy duty in the Eastern Mediterranean, operating out of a base at Malta. It took some prodding to induce the Japanese to perform this service, however; significantly, they hesitated for fear that any meaningful reduction in their own naval strength in the Pacific would result in American gains at their expense.

This latter observation points to one of the weaknesses of Allied coalition building. The Japanese were not alone in joining the Allies out of some expectation of territorial aggrandizement; most countries that rallied to the Allied cause did so in expectation of some gains, and in many cases these expectations were validated by the senior Allied partners, as was the case for Japan. Widely-ranging demands complicated the prospects for peace, however, and when the Allies were finally ready to discuss terms in 1918, it was soon decided that Britain, France, the United States and Italy would dominate the proceedings. Of these, Italy was only technically a leading power. Most decisions were in the hands of the first three nations, and nations like Japan were only consulted in connection with issues directly related to their spheres of influence.

This is yet another way that the Treaty of Versailles planted the seeds of future conflicts. To Japan, it constituted proof that the Western powers failed to respect Japan, and that the Japanese could not expect a fair chance from their former partners. At the same time, China was outraged that part of its territory, Shantung, would be handed over to Japan, even though it was technically an Allied power in its own right, having declared war in 1917. These developments served to fuel Japanese interests in expanding their influence in China while hardening Chinese resolve to resist the Japanese.

Japan joined the Allied cause in the first weeks of the war. It served ably in a limited capacity, and made real contributions to Allied victory. At the same time, it was motivated primarily by a desire for territorial aggrandizement. These goals were realized in the opening phases of the war, but it became clear by the end of the war that further gains would not be expected in concert with other Allied powers. This prompted Japan after the war to pursue a course of aggressive expansion without regard for foreign opinion, and this led directly to World War II.



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Forty, Simon.  World War I: A Visual Encyclopedia. PRC Publishing, 2002

Haythornthwaite, Philip J.  The World War One Source Book.  Arms & Armour, 1996

Livesey, Anthony.  The Historical Atlas of World War I.  Henry Holt, 1994

Strachan, Hew.  The Oxford Illustrated History of the First World War. Oxford, 2001

Willmott, H.P.  World War I.  Covent Garden Books, 2003


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