Japanese entry into World War I
Japan entered World War I as a member of the Allies on 23 August 1914, seizing the opportunity of Imperial Germany's distraction with the European War to expand its sphere of influence in China and the Pacific. There was minimal fighting. Japan already had a military alliance with Britain, but that did not obligate it to enter the war. It joined the Allies in order to make territorial gains. It acquired Germany's scattered small holdings in the Pacific and on the coast of China.
The other Allies pushed back hard against Japan's efforts to dominate China through the Twenty-One Demands of 1915. Japan's occupation of Siberia against the Bolsheviks proved unproductive. Japan's wartime diplomacy and limited military action produced few results. At the Paris Peace Conference in 1919, Japan was largely frustrated in its ambitions.
Operations against Germany[edit]
The onset of the First World War in Europe eventually showed how far German–Japanese relations had truly deteriorated. On 7 August 1914, only three days after Britain declared war on the German Empire, the Japanese government received an official request from the British government for assistance in destroying the German raiders of the Kaiserliche Marine in and around Chinese waters. Japan, eager to reduce the presence of European colonial powers in South-East Asia, especially on China's coast, sent Germany an ultimatum on 14 August 1914, which was left unanswered. Japan then formally declared war on Germany on 23 August 1914 thereby entering the First World War as an ally of Britain, France and Russia. It promptly seized the German-held Caroline, Marshall, and Mariana Islands in the Pacific.
The only major battle that took place between Japan and Germany was the siege of the German-controlled Chinese port of Qingdao in Kiautschou Bay. The German forces held out from August until November 1914, under a total Japanese/British blockade, sustained artillery barrages and manpower odds of 6:1 – a fact that gave a morale boost during the siege as well as later in defeat. After Japanese troops stormed the city, the German dead were buried at Tsingtao and the remaining troops were transported to Japan where they were treated with respect at places like the Bandō Prisoner of War camp.[9] In 1919, when the German Empire formally signed the Treaty of Versailles, all prisoners of war were set free and returned to Europe.
Japan was a signatory of the Treaty of Versailles, which stipulated harsh repercussions for Germany. In the Pacific, Japan gained Germany's islands north of the equator (the Marshall Islands, the Carolines, the Marianas, the Palau Islands) and Kiautschou/Qingdao in China.[10] Article 156 of the Treaty also transferred German concessions in Shandong to Japan rather than returning sovereign authority to the Republic of China, an issue soon to be known as Shandong Problem. Chinese outrage over this provision led to demonstrations, and a cultural movement known as the May Fourth Movement influenced China not to sign the treaty. China declared the end of its war against Germany in September 1919 and signed a separate treaty with Germany in 1921. This fact greatly contributed to Germany relying on China, and not Japan, as its strategic partner in East Asia for the coming years.[11]
Operations against China[edit]
In 1914, Japanese and British military forces liquidated Germany's holdings in China. Japan occupied the German military colony in Qingdao, and occupied portions of Shandong Province. China was financially chaotic, highly unstable politically, and militarily very weak. China declared war on Germany in August 1917 as a technicality to make it eligible to attend the postwar peace conference, where they hoped to find friends who would help block the threats of Japanese expansion. They planned to send a combat unit to the Western Front, but never did so.[12][13] British diplomats were afraid that the U.S. and Japan would displace Britain's leadership role in the Chinese economy. They sought to play Japan and the United States against each other, while at the same time maintaining cooperation among all three nations against Germany.[14]
In January 1915, Japan secretly issued an ultimatum of Twenty-One Demands to the Chinese government. They included Japanese control of former German rights, 99 year leases in southern Manchuria, an interest in steel mills, and concessions regarding railways. China did have a seat at the Paris Peace Conference in 1919. However, it was refused a return of the former German concessions and China had to accept the Twenty-One demands. A major reaction to this humiliation was a surge in Chinese nationalism expressed in the May Fourth Movement.[15]