Excerpts from Books and Wikipedia
"At war with China since 1937, the Japanese decided in 1941 to take a gamble that, if successful, would secure them an empire in Asia and the Pacific. On December 7, they attacked the US base at Pearl Harbor in Hawaii and launched an invasion of the Philippines and European colonies in Southeast Asia. The British and Dutch colonies in Southeast Asia proved easy prey for Japan--the British base at Singapore fell with virtually no resistance. Within five months, the Japanese had reached the border of British India in Burma. Australia seemed threatened, but Japan's southward push was checked by a clash with US aircraft carriers at the Battle of the Coral Sea. A new phase of the war began with an ambitious thrust by the Japanese navy against Midway Island, which led to heavy losses. From August 1942, the most intense fighting focused around Guadalcanal, which the US eventually held. It was not until 1944 that the US had built up sufficient strength for a sustained advance. The Japanese navy was routed at the battles of the Philippine Sea and Leyte Gulf, while the seizure of the Mariana Islands brought the Japanese within range of US bomber aircraft." [Smithsonian, p. 394]