In the months leading up to the operation, Japanese airpower on Bougainville was degraded by Allied air strikes, while small parties of Allied reconnaissance forces landed around Bougainville and the surrounding islands to gather intelligence. On 1 November, a landing force based around the US 3rd Marine Division, reinforced with various supporting elements, landed at Empress Augusta Bay, on the western side of Bougainville. Situated well away from the main Japanese troop concentrations, the landing was met with only limited resistance on the ground. Japanese aircraft from Rabaul attempted to interdict the landing force, but their attacks proved ineffective and they were largely fought off by US and New Zealand fighters. By the end of the first day, a small perimeter had been established and the majority of the first wave of transports had unloaded their stores over the beachhead.