Strategic Setting

During a series of conferences dating from January 1941 the combined ground, sea, and air chiefs of staff of the United States and the United Kingdom discussed strategies to defeat the Axis Powers and listed the priorities that should guide their efforts toward that end. Although they conferred as allies, the two Atlantic partners had to refer to themselves as Associated Powers while the United States remained neutral. As the major decision of these conferences, the Associated Powers agreed on a Germany-first strategy: the anti-Axis coalition would concentrate on the defeat of Nazi Germany and Italy before turning its collective war-making power against Japan. Until the European Axis partners surrendered, the Associated Powers would mount only limited offensives in the Pacific to contain the Japanese. Decisions supportive of the Germany-first priority included a division of the world into areas of military responsibility reflecting the respective military potential of the major powers in various geographical areas. The British would concentrate their efforts in western Europe and the Mediterranean theaters, while the United States would carry the burden of limited offensives in the Pacific.

On 30 March 1942, the American Joint Chiefs of Staff made a further division of responsibility for the War and Navy Departments. The U.S. Navy assumed operational responsibility for the vast Pacific Ocean Areas and gave the new command to Admiral Chester W. Nimitz, commander in chief of the Pacific Fleet since shortly after the attack on Pearl Harbor. The U.S. Army took operational control of the Southwest Pacific Area, assigning the command to General Douglas MacArthur, recently ordered from the Philippines to Australia. MacArthur's new command encompassed the seas and archipelagos south of Formosa and the Carolines, east of the Malay Peninsula, and west of New Caledonia, an area including the Philippines, the Netherlands East Indies, Australia, and New Guinea. On 20 April the Joint Chiefs established a subdivision of the Navy's Pacific Ocean Areas command - the South Pacific Area, under Vice Adm. Robert L. Ghormley - which included New Zealand, important island bases at the end of the South Pacific ferry route from Hawaii, and the Solomons, a former British protectorate only 500 miles east of New Guinea. Ghormley had the mission of blocking the Japanese before they cut the South Pacific ferry route and severed Australia and New Zealand from the United States. The line between MacArthur's Southwest Pacific Area command and Ghormley's South Pacific Area command divided the Solomons at a point 1,100 miles northeast of Australia. Obviously, any operations in defense of Australia or New Zealand and the South Pacific ferry route would depend on close Army-Navy cooperation.