During the spring of 1943 after losing the Philippines the Allies began to formulate the ultimate strategy for defeating Japan. The objective was control of the South China Sea and a foothold in China to sever Japanese communication and provide a base of operations to subject mainland Japan to aerial bombardment. Other objectives included establishing a naval blockade and an invasion as a last resort. To achieve these objectives two routes toward Japan were created. One was the Central Pacific plan via the Gilberts, Marshalls, Marianas and Palau toward the Philippines or Taiwan. The Southwest Pacific route went via New Guinea, Vogelkep and to the Philippines. Although the US command preferred the Central Pacific route, neither gained operational favor.
In 1942 General MacArthur had been driven from the Philippines and his island hopping approach from Central and Southwest Pacific decimated Japanese forces, forcing them to withdraw to the mainland. Once the mainland was successfully cutoff from re-supply and Japanese naval and ground forces were effectively destroyed outside Japan, the United States halted their advancement. During this time President Roosevelt offered to let Japan surrender. Japan refused based on flawed intelligence indicating the US would overwhelm and enslave the people. President Roosevelt was left with a difficult choice. It was estimated a million men would be lost in an invasion of Japan. To keep such a large loss of men from occurring, Roosevelt ordered the use of the atomic weapon on Hiroshima. He offered the Japanese another chance to surrender, but they again refused. This led to the second use at Nagasaki. The unyielding pressure of the atomic devastation and supplies blockaded by the Navy forced Japan to surrender to the US.