1914-18: Japanese involvement in the First World War
During WW1, Japan honoured the Anglo-Japanese Alliance of 1902 as it entered the war against Germany and it’s allies.
Japan increased trade with the far east and provided goods which Europeans no longer could due to war and fighting.
They invaded and occupied Chinese territory which was owned by the Germans.
Meanwhile, they provided the European allies which were in the war with essential shipping and goods.
During the first world war, Japan declared war on Germany, seizing Germany's military bases on the Shandong Peninsula in the north of China, while its navy occupied Germany's South Pacific possessions.
Japan was able to expand and train its army by fighting in the First World War.
Meanwhile, it was able to expand its economy due to increased trading.
Finally, it gained land as it captured German-owned Chinese territories.
In 1915, they released their 21 demands of China. Prior to joining the War, the allies had promised them the recognition of Japanese control over previously German-administered areas of China, including the Shandong province. However, their demands resulted in anger in China, and protests in major chinese cities. (see 1919: The May the Fourth Movement)