The Pacific War was the part of World War II—and preceding conflicts—that took place in the Pacific Ocean, its islands, and in East Asia.

The war began as a conflict with the Empire of Japan and the Republic of China in July 7, 1937, but by December, 1941, became part of the greater World War II, and lasted until August 14, 1945. The Pacific War saw the Allied powers against the Empire of Japan, the latter aided by Thailand and to lesser extent by its Axis allies Germany and Italy.

The most decisive actions took place after the Empire of Japan attacked various countries, most notably the Bombing of Pearl Harbor in the United States Territory of Hawaii, who together came to be known as the Allies (or Allied powers).

The Pacific War culminated in the Atomic bombings of Hiroshima and Nagasaki by the United States and Soviet invasion of Manchuria, resulting in VJ Day and the end of World War II on August 15, 1945. The unconditional Surrender of Japan occurred aboard the USS Missouri on September 2, 1945.