Why Japan joined the First World War and her gains between 1914 and 1919.

Japan joined the First World War in August 1914 because of the following reasons.

Further Japan’s imperialism - a fundamental factor was Japan’s quest for imperial gains. Having succeeded in her modernization, Japan’s concern for security quickly changed into a desire for imperial adventure. This change was natural because the great powers of the world had colonial empires and Japan was only following their examples. Thus far, she had defeated both China and Russia, and these victories paid high dividends. Now, she was looking for more gains. The main goal was to dominate an area comprising China, Manchuria, Korea, and the adjacent Pacific islands. The European powers’ preoccupation with the great war gave Japan an opportunity for adventure and a declaration of war on Germany gave her a pretext for aggression. Furthermore, by participating in the war on the part of the Allied powers, Japan could enhance her international status. That finally the powers requested Japan’s assistance in war, especially in naval operations, was a demonstration of Japanese strength and power.

Pro-British sentiment - when the European war broke out, the Japanese government under Okuma (Prime Minister) and Kato Komei (Foreign Minister) was willing to exploit it. Both were supporters of the Anglo-Japanese Alliance. The question was whether Japan’s alliance with Britain, even though it did not apply specifically to Europe, imposed on her military obligations in such a situation. Britain, after her declaration of war on Germany, sought Japan’s help in protecting Hong Kong and Weihaiwei. Kato, to go further, preferred war in order to fish in troubled water, and he succeeded in persuading the cabinet and the Genro to his viewpoint.

Fish in troubled water - Kato had in mind the German possessions in China and in the Pacific. These included the German sphere of influence in Shantung and a chain of German-held Pacific-islands north of the equator (Marshalls, Marianas, Carolines). By taking advantage of Europe’s preoccupation with the war, Japan could seize these possessions first, and thereby increased Japan’s power and influence tremendously. Should Japan and the Allies win the war, Japan could formally take over these German interests in the peace conference.
Yet it ought to be remembered that the taking over of German interests in Asia was only part of Japan’s goal. She also had an eye on China.

Revenge on Germany - a Japanese declaration of war on Germany, apart from material gains, would allow her to take revenge on Germany for the Triple Intervention in 1895. The Japanese had not forgotten this diplomatic humiliation. Having defeated Russia, a member of the Triple Intervention, ten years ago, it was now Germany’s turn to fact a Japanese revenge. On August 23, 1914, Japan declared war on Germany. This was followed by prompt and successful military actions. During and after the First World War, Japan’s gains were enormous.

Taking over German interests 1914 - having declared war on Germany, Japan landed troops on the German sphere of interest in China - Shantung peninsula. By November 1914, Japan had control over the region, taking in hex possession the Kiaochow Bay, Tsingtao-Tsinan Railway, and other German interests. At the same time, Japan’s naval operations had led to the occupation of the German-held Pacific islands north of the equator. These included the Marshalls, Marianas, and Carolines.

The Twenty-One Demands 1915 - when the powers were busy in Europe, Japan took the opportunity and presented the Twenty-One Demands to China in January 1915. The terms of the Twenty-One Demands could be divided into five main groups:

1. Japan would get all the former German rights in Shantung. (This meant a Chinese recognition of a fait accompli since Japanese troops were already there)
2. Japan would get mining and railway rights in Manchuria and Mongolia, as well as other economic and political privileges in the region.
3. Japan should have economic rights in the Yangtze region. (A challenge to Britain since the Yangtze area was a British sphere of interest)
4. China was not to cede or lease any coastal area to another power. (Non-alienation of Chinese territories)
5. Japanese political, financial and military advisers were to be appointed in China to advise the Chinese government. (This would mean a Japanese protectorate over China)

President Yuan Shikai was forced to agree to most of the terms except those of group 5. Chinese reaction to this was violent. Hatred of Japan was widespread. The western powers were not happy either. The strongest protest came from the United States. Yet between 1916 and 1917, the major western powers including Britain, Russia, France, Italy, and the United States signed secret agreements with Japan, recognizing her gains in China and in the Pacific. Their main considerations were to keep Japan in the war against the Central Powers and to secure Japan’s naval assistance in the Pacific.

Wartime economic gains - before 1914, Japan’s financial and economic conditions were neither stable nor healthy. The chief problems were the balance of payments (imports exceeded exports) and the accelerating rise in the rate of population growth. The situation was radically changed by the First World War. During the war years, the vacuum left in Asia with the withdrawal of European goods was filled by Japanese manufactures. The number of factory workers almost doubled, as did the export of cotton goods. At the same time, Japan produced strategic materials and armaments to supply the Allies. The destruction of European shipping benefitted the Japanese merchant marine which almost doubled in size (from 1.5 million tons to 3 million tons) and increased its net freight income about ten times (reaching over 400 million yen).
Then, it was not long before Japan became a creditor instead of a debtor among the nations. Her growing foreign trade had turned an average import surplus of 65 million yen into an export surplus of 350 million yen. By 1920, Japan had gold reserves at home and abroad of more than 2 billion yen.

Versailles Conference 1918-9 - in the Versailles Conference, Japan’s delegates ranked only next to the United States, Britain, and France. She was regarded as a fourth great power in the world. Since Japan had secret agreements with the powers over her wartime gains in China, she was able to retain her gain in Shantung though China protested vigorously and refused to sign the peace treaties. She also acquired mandatory power over the German islands in the Pacific north of the equator. Japan was also given a permanent seat in the Council of the League of Nations. Yet, her delegates failed to get inserted in the League’s Covenant a declaration of the principle of racial equality.

Conclusion - in the words W.G. Beasley, “By 1918, when the war ended, (Japan had become) a world power, with a military and naval establishment capable of giving substance to the rights she claimed, as well as an economy far enough developed to support her forces, population and prestige.”