In 1941-42 the Japanese conquered an empire in Southeast Asia. The turning point for them was the great battle of Guadalcanal. It marked the beginning of their retreat, in the same way that the defeat of Stalingrad in 1942 was the turning point for the Germans in Russia. The battle started with the landing of US Marines on the island of Guadalcanal in August 1942. The Marines, who were very tough fighters, took the airstrip but had to fight a hard campaign in hot, steamy jungles and swamps to hold it. The Japanese returned again and again to reclaim the island and finally gave up only in February 1943 after six months of heavy fighting, several sea battles and the loss of many lives. The American Marines then advanced along the chain of the Solomon Islands.

While the battle for Guadalcanal was fought, MacArthur led Americans and Australians on a hard trek through 160 km of jungles and mountains from Port Moresby across Papua to Buna. He then advanced slowly along the coast of New Guinea in a series of landings from the sea. The large Japanese base at Rabaul was boxed in from north and south. And MacArthur's troops slowly continued their advance northwards.

The American strategy in the Pacific war was then to make two great drives which were to meet if the Philippine Islands and then push northwards towards Japan, by-passing and cutting off the major Japanese bases at Rabdtil and Truk. These drives were:

1. The US Army's drive along the New Guinea coast, with the Australians, under MacArthur.
2. The US Navy's Central Pacific Drive, directed by Admiral Nimitz from Pearl Harbour.

The Central Pacific Drive began in November 1943 with the landings on the Gilbert Islands. These are a group of atolls (islands on coral reefs). Although one of the atolls was captured quite easily the assault on Tarawa Atoll was difficult and bloody. The Japanese had dug deep bombproof shelters and fought to the death to defend the islands, since to surrender was considered dishonourable by the Japanese. Shelling and bombing failed to destroy the Japanese strongpoints and the Marines had to clear them out one by one with flame-throwers and grenades. The loss of life was enormous. In three days of fighting more than 3000 Marines were killed or wounded and the Americans counted 4690 dead Japanese.

The US 5th Fleet, under Admiral Spruance, then headed for the Marshall Islands where they took Kwajalein Ato11 in 1944.

In the 5th Fleet there was a mass of landings on the Japanese-held islands. The 5th Fleet was protected by the Fast Carrier Task Force (TF 58) of eight heavy aircraft carriers and eight light carriers, accompanied by modern battleships and cruisers. This exceptionally powerful fleet was like a huge floating air base with about 1000 aircraft. Such sea and air power had never been seen before. Making great lunges across the ocean, these fleets were at sea for as long as three months at a time. In the south-west, MacArthur continued his advances, supported by the American 7th Fleet.

In June 1944 the US 5th Fleet made the long voyage of 1500 km to SaiDan in the Mariana Islands, from where the Japanese homeland could be bombed. The Marines had a very hard fight to take Saipan. The mass suicide here of Japanese civilians, throwing themselves off a cliff, showed the fanatical resistance to be expected if Japan itself were invaded.