The Allies of World War II conducted an air attack upon a cruiser force at the major Japanese base of Rabaul in November 1943. In response to the Allied invasion of Bougainville, the Japanese had brought a strong cruiser force down from Truk, their major naval base in the Caroline Islands about 800 miles north of Rabaul, to Rabaul in preparation for a night engagement against the Allied supply and support shipping. Allied carrier- and land-based planes attacked the Japanese ships, airfields, and port facilities on the island of New Britain to protect the Allied amphibious invasion of Bougainville. As a result of the Rabaul raids, the Japanese naval forces could no longer threaten the landings. The success of the raid began to change the strongly held belief that carrier-based air forces could not challenge land-based air forces. Background In early 1943, Rabaul had been distant from the fighting. However, the Allied grand strategy in the South West Pacific Area—Operation Cartwheel—aimed to isolate Rabaul and reduce it by air raids. Japanese ground forces were already retreating in New Guinea and in the Solomon Islands, abandoning Guadalcanal, Kolombangara, New Georgia and Vella Lavella. Rabaul—on the island of New Britain—was one of two major ports in the Australian Territory of New Guinea. It was the main Japanese naval base for the Solomon Islands campaign and New Guinea campaign. Simpson Harbor—captured from Australian forces in February 1942—was known as "the Pearl Harbor of the South Pacific" and was well defended by 367 anti-aircraft guns and five airfields. Lakunai and Vunakanau airfields were prewar Australian strips. Lakunai had an all-weather runway of sand and volcanic ash, and Vunakanau was surfaced with concrete. Rapopo— to the southeast—became operational in December 1942 with concrete runways and extensive support and maintenance facilities. Tobera—completed in August 1943 halfway between Vunakanau and Rapopo—also had concrete strips. The four dromes had 166 protected revetments for bombers and 265 for fighters, with additional unprotected dispersal parking areas. The fifth airfield protecting Rabaul was Borpop airfield, completed in December 1942 across the St. Georges Channel on New Ireland. The anti-aircraft defenses were well coordinated by army and naval units. The army operated 192 of the 367 antiaircraft guns and the navy 175. The naval guns guarded Simpson Harbor and its shipping and the three airfields of Tobera, Lakunai, and Vunakanau. The army units defended Rapopo airfield, supply dumps and army installations; and