In July 1942, the Joint Chiefs of Staff approved a series of operations against the Japanese bastion at Rabaul, which blocked any Allied advance along the northern coast of New Guinea towards the Philippines or northward towards the main Japanese naval base at Truk. In keeping with the overall Allied grand strategy of Europe first, the immediate aim of these operations was not the defeat of Japan but merely the reduction of the threat posed by Japanese aircraft and warships based at Rabaul to air and sea communications between the United States and Australia. By agreement among the Allied nations, in March 1942 the Pacific theatre was divided into the South West Pacific Area, under General Douglas MacArthur, and the Pacific Ocean Areas, under Admiral Chester W. Nimitz. Rabaul fell within MacArthur's area but the initial operations in the southern Solomon Islands came under Nimitz. The Japanese reaction was more violent than anticipated and some months passed before the Guadalcanal Campaign was brought to a successful conclusion. Meanwhile, General MacArthur's forces—primarily Australian—fought off a series of Japanese offensives in Papua in the Kokoda Track Campaign, Battle of Milne Bay, Battle of Buna-Gona, and the Battle of Wau.