 Two months later, the Allies took advantage of Japan's resulting strategic vulnerability in the South Pacific and launched the Guadalcanal Campaign; this, along with the New Guinea Campaign, eventually broke Japanese defenses in the South Pacific and was a significant contributing factor to Japan's ultimate surrender in World War II.On December 8, 1941 (December 7 US time), Japan declared war on the US and the British Empire, after Japanese forces attacked Malaya, Singapore and Hong Kong as well as the US naval base at Pearl Harbor.In launching this war, Japanese leaders sought to neutralize the U.S. fleet, seize territory rich in natural resources, and obtain strategic military bases to defend their far-flung empire.