Following the attack on Pearl Harbor, the Japanese launched offensives against Allied forces in South East Asia, with simultaneous attacks on Hong Kong, British Malaya and the Philippines.

In Malaya the Japanese overwhelmed a Commonwealth army composed of British, Indian, Australian and Malay forces. The Japanese were quickly able to advance down the Malayan peninsula, forcing the Commonwealth forces to retreat towards Singapore. The British lacked aircover and tanks; the Japanese had total air superiority. The sinking of HMS Prince of Wales and HMS Repulse on December 10, 1941 led to the east coast of Malaya being exposed to Japanese landings and the elimination of British naval power in the area. By the end of January 1942, the last Allied forces crossed the strait of Johore and into Singapore. Hong Kong surrendered to the Japanese on Christmas Day.

In the Philippines the Japanese pushed the combined Filipino-American force towards the Bataan peninsula and later the island of Corregidor. By January 1942 General Douglas MacArthur and President Manuel L. Quezon were forced to flee in the face of Japanese advance. This marked among one of the worst defeats suffered by the Americans, leaving over 70,000 American and Filipino prisoners of war in the custody of the Japanese.

On February 15, 1942 Singapore due to the overwhelming superiority of Japanese forces and encirclement tactics fell to the Japanese, caused about the largest surrender of British-led military personnel in history. An estimated 80,000 Indian, Australian and British troops were prisoners of war, joining 50,000 taken in the Japanese invasion of Malaya (modern day Malaysia), many later used as forced labour constructing the Burma Railway, the site of the infamous Bridge on the River Kwai.

Due to the United States blockade and embargo of raw material, the Japanese military industrial complex sought raw materials elsewhere and turned their attention to the vast steel, (latex) rubber, coal and oil riches of South-East Asia. The Japanese swept into relatively lightly guarded Burma (modern-day Myanmar), the well-defended British Malaya states and the heavily fortified Fortress Singapore Singapore for highly strategic control of major trans-Pacific shipping routes.

The Japanese then seized the key oil production zones of Borneo (modern day Brunei), Central Java, Malang, Cepu, Sumatra, and Dutch New Guinea (modern day Indonesian province of Irian Jaya, also conveniently abundant in highly valuable copper) of the late Dutch East Indies, defeating the Dutch forces and welcomed ecstatically as liberating heroes by the oppressed Indonesian natives pursuant to their indigenous legends. The Japanese then consolidated their lines of supply through capturing key islands of the Pacific, including Guadalcanal.

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