The naval and amphibious engagements in the Pacific during World War II. The war spread to the Pacific when Japanese aircraft attacked the US naval base of Pearl Harbor in 1941. Japan was allied to Thailand and had bases in Vichy-controlled Indo-China. Its landforces quickly occupied Hong Kong, Malaya, Singapore, and Burma. Other Japanese forces captured islands in the Pacific, while convoys sailed to occupy Borneo and the Dutch East Indies following the Japanese naval victory at the Battle of the Java Sea (27 February–1 March 1942). By April the Philippines were occupied, followed by northern New Guinea, and General MacArthur withdrew to Australia, where he organized a counter-attack. The Battle of the Coral Sea (5–8 May) between Japanese and US aircraft carriers was strategically a US victory. It prevented Japanese landings on southern New Guinea and ended their threat to Australia. It was followed (3–6 June) by the decisive Battle of Midway Island, which, under Admiral Nimitz, shifted the balance of naval power to the USA. In August 1942 US marines landed on Guadalcanal and Tulagi in the Solomon Islands, where fighting raged until February 1943. During 1943, the remaining Solomon Islands were recaptured by the USA; Bougainville was reclaimed from the Japanese in November, followed by New Britain early in 1944. In June 1943 MacArthur had launched his campaign to reoccupy New Guinea, and through 1944 US forces gradually moved back towards the Philippines. On 19 June 1944 the Japanese lost some 300 planes in the Battle of the Philippine Sea and in July the USA took the Mariana Islands, from which bombing raids on Tokyo were then organized. In October 1944 the Battle of Leyte Gulf marked the effective end of Japanese naval power, while on the mainland the Burma Campaign had reopened land communication with China and begun the process of reoccupation of the short-lived Japanese empire. Manila fell in March 1945, and in April US forces reoccupied Okinawa against fierce kamikaze air raids, at the cost of very high casualties on both sides. Plans to invade Japan were ended by the decision to drop atomic bombs on Hiroshima and Nagasaki (6 and 9 August), which resulted in Japanese surrender.