South West Pacific theatre of World War II

The South West Pacific theatre, during World War II, was a major theatre of the war between the Allies and the Axis. It included the Philippines, the Dutch East Indies (except for Sumatra), Borneo, Australia, its mandate Territory of New Guinea (including the Bismarck Archipelago) and the Solomon Islands' western part. This area was defined by the Allied powers' South West Pacific Area (SWPA) command.

Japanese forces fought primarily against the United States and Australian forces in the South West Pacific theatre. The Philippines, New Zealand, the Netherlands (in the Dutch East Indies), the United Kingdom, and other Allied nations also contributed forces.

The South Pacific became a major theatre of the war following the Japanese attack on Pearl Harbor in December 1941. Initially, US war plans called for a counteroffensive across the Central Pacific, but this was disrupted by the loss of battleships at Pearl Harbor. During the First South Pacific Campaign, US forces sought to establish a defensive perimeter against additional Japanese attacks. This was followed by the Second South Pacific Campaign, which began with the Battle of Guadalcanal.