Japan during World War I Japan during World War I Japan participated in World War I from 1914 to 1918 in an alliance with Entente Powers and played an important role in securing the sea lanes in the West Pacific and Indian Oceans against the Imperial German Navy as the member of the Allies. Politically, the Japanese Empire seized the opportunity to expand its sphere of influence in China, and to gain recognition as a great power in postwar geopolitics. Japan's military, taking advantage of the great distances and Imperial Germany's preoccupation with the war in Europe, seized German possessions in the Pacific and East
Declarations of war during World War II 1907 (or Hague II). For the diplomatic maneuvering behind these events, which led to hostilities between nations during World War II, see the article entitled Diplomatic history of World War II. Below is a table showing the outbreak of wars between nations which occurred during World War II. Indicated are the dates (during the immediate build-up to, or during the course of, World War II), from which a "de facto" state of war existed between nations. The table shows both the "Initiator Nation(s)" and the nation at which the aggression was aimed, or "Targeted Nation(s)". Events listed include those in