 Complete the following phrase:  Japanese forces had landed on Bougainville in early 1942, capturing it from the small force of Australians garrisoning the island. They had subsequently developed several airbases on the island, using it to conduct operations in the northern Solomon Islands and to attack the Allied lines of communication between the United States, Australia and the Southwest Pacific Area. These bases also helped protect Rabaul, the major Japanese garrison and naval base in Papua New Guinea, and throughout 1943, Allied planners determined that Bougainville was vital for neutralising the Japanese base around Rabaul. US Marines conducted an 