South-West Pacific Area

South-West Pacific Area (SWPA), US theatre of operations commanded by General MacArthur during the Pacific war. Its GHQ, established in Brisbane in April 1942, commanded an area which took in Australia, the Philippines, New Guinea, Bismarck archipelago, Solomon Islands, and the Netherlands East Indies (except Sumatra). In August 1942 the boundary was changed to exclude Guadalcanal and certain other Solomon islands, which the US Joint Chiefs of Staff had ordered the commander of the South Pacific Area to seize.

All Allied combat echelons in the area were assigned to MacArthur. An Australian, General Blamey, was appointed his Allied Land Forces commander, while two US officers, Lt-General George Brett and Vice-Admiral Herbert Leary, were appointed his Allied Air Forces and Allied Naval Forces commanders. In July 1942 Lt-General George C. Kenney, who also commanded SWPA's Fifth USAAF (and later Thirteenth USAAF as well), replaced Brett; in September 1942 Vice-Admiral Arthur Carpender, who also commanded SWPA's Seventh Fleet, replaced Leary; and in November 1943 Vice-Admiral Thomas Kinkaid replaced Carpender. In August 1942 Lt-General Eichelberger was appointed corps commander of two US infantry divisions (32nd and 41st) which had been sent to reinforce Australia. These initially came under Blamey's command, but in June 1943 MacArthur formed Alamo Force which effectively removed all US ground forces from Blamey's operational command. These forces became part of Sixth US Army, formed in February 1943 under Lt-General Walter Krueger, and Eichelberger's Eighth US Army, formed in October 1944.

The two organizations formed to provide MacArthur with intelligence were the Allied Intelligence Bureau, which controlled all intelligence operations in SWPA, and Central Bureau, Mac Arthur's decoding establishment. Central Bureau played a major role in providing ULTRA intelligence and by August 1945 numbered more than 4,000 men and women from several Allied countries.