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South West Pacific theatre of World War II

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Australian troops at Milne Bay, New Guinea. The Australian army was the first to inflict defeat on the Imperial Japanese Army during World War II at the Battle of Milne Bay of August–September 1942.

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 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 (in the Dutch East Indies), the Philippines, 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.

Allied command[edit]

Australian cruiser Canberra (center left) protects three Allied transport ships (background and center right) unloading troops and supplies at Tulagi.

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 Southeast 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 Commander, South West Pacific Area on 30 March 1942.[1][2] However, MacArthur preferred to use the title "Commander-in-Chief." The forces remaining in South-East Asia under Japanese attack reverted to their local commanders, and were soon mostly destroyed or evacuated.

The other major theatre in the Pacific, Pacific Ocean Areas, was commanded by U.S. Admiral Chester Nimitz, who was also Commander-in-Chief Pacific Fleet. Both MacArthur and Nimitz were overseen by the US Joint Chiefs and the British-U.S. Combined Chiefs of Staff. Captain Allan Rockwell McCann was appointed to represent the Navy as the Senior Representative of Commander, Submarines, Southwest Pacific, to General MacArthur.

Japanese command[edit]

Most Japanese forces in the theatre were part of the Southern Expeditionary Army (南方軍, Nanpo gun), which was formed on November 6, 1941, under General Hisaichi Terauchi (also known as Count Terauchi). The Nanpo gun was responsible for Imperial Japanese Army (IJA) ground and air units in Southeast Asia and the South Pacific. The Combined Fleet (聯合艦隊, Rengō Kantai) of the Imperial Japanese Navy (IJN) was responsible for all Japanese warships, naval aviation units and marine infantry units. As the Japanese military did not formally utilize joint/combined staff at the operational level, the command structures/geographical areas of operations of the Nanpo gun and Rengō Kantai overlapped each other and those of the Allies.

Major campaigns[edit]

Japanese troops load onto a warship in preparation for a Tokyo Express run sometime in 1942.
A U.S. A-20G bomber of the 3rd Attack Group bombs a Japanese merchant ship off New Guinea during the Battle of the Bismarck Sea, March 1943.
Gen. Douglas MacArthur wades ashore during initial landings at Leyte, Philippine Islands, 20 October 1944.
U.S.-manned Alligators transport Australian troops during the Battle of Balikpapan, Borneo, 1 July 1945.


  1. ^ Cressman 2000, p. 84.
  2. ^ Milner 1957, p. 22.
  3. ^ Dull 1978, p. 61.
  4. ^ a b c Silverstone 1968, pp. 9–11.
  5. ^ Dull 1978, p. 75.
  6. ^ Dull 1978, p. 91.
  7. ^ a b c d e f Potter & Nimitz 1960, p. 732.
  8. ^ a b c d Potter & Nimitz 1960, p. 759.
  9. ^ a b c d Sulzberger 1966, pp. 332–333.


  • Cressman, Robert J. (2000). The Official Chronology of the U.S. Navy in World War II. Annapolis, Maryland: Naval Institute Press. ISBN 1-55750-149-1.
  • Dull, Paul S. (1978). A Battle History of the Imperial Japanese Navy (1941–1945). Annapolis, Maryland: Naval Institute Press.
  • Milner, Samuel (1957). Victory in Papua (PDF). Washington, D.C.: United States Army Center of Military History. LCCN 56-60004. OCLC 220484034. Archived from the original (PDF) on 6 May 2017. Retrieved 9 July 2012.
  • Potter, E.B.; Nimitz, Chester W. (1960). Sea Power. Prentice-Hall.
  • Silverstone, Paul H. (1968). U.S. Warships of World War II. Doubleday and Company.
  • Sulzberger, C.L (1966). The American Heritage Picture History of World War II. Crown Publishers.

Further reading[edit]