South West Pacific Area (SWPA) was the name given to the Allied supreme military command in the South West Pacific Theatre of World War II. It was one of four major Allied commands in the Pacific War. SWPA included the Philippines, Borneo, the Dutch East Indies (excluding Sumatra), East Timor, Australia, the Territories of Papua and New Guinea, and the western part of the Solomon Islands. It primarily consisted of United States and Australian forces, although Dutch, Filipino, British and other Allied forces also served in the SWPA.

General Douglas MacArthur was appointed as the Supreme Commander, Southwest Pacific Area, on its creation on 18 April 1942. He created five subordinate commands: Allied Land Forces, Allied Air Forces, Allied Naval Forces, United States Army Forces in Australia (USAFIA), and the United States Army Forces in the Philippines. The last command disappeared when Corregidor surrendered on 6 May 1942, while USAFIA became the United States Army Services of Supply, Southwest Pacific Area (USASOS SWPA). In 1943, United States Army Forces in the Far East was reformed and assumed responsibility for administration, leaving USASOS as a purely logistical agency. Both were swept away in a reorganisation in 1945. The other three commands, Allied Land Forces, Allied Air Forces and Allied Naval Forces, remained until SWPA was abolished on 2 September 1945.

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

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

Allied command

The U.S. General Douglas MacArthur had been in command of the American forces in the Philippines in what was to become the South West Pacific theatre, but was then part of a larger theatre that encompassed the South West Pacific, the South East Asian mainland (including Indochina and Malaya) and the North of Australia, under the short lived American-British-Dutch-Australian Command (ABDACOM). Shortly after the collapse of ABDACOM, supreme command of the South West Pacific theatre passed to MacArthur who was appointed Supreme Allied Commander South West Pacific Area on 30 March 1942. In the other major theatre in the Pacific region, known as the Pacific Ocean theatre, Allied forces were commanded by US Admiral Chester Nimitz. Both MacArthur and Nimitz were overseen by the US Joint Chiefs and the western Allies Combined Chiefs of Staff (CCoS).