Allied planners had seriously underestimated the strength and effectiveness of Japanese Forces. Allied opinion held that they could not shoot straight, since many Japanese were nearsighted. Despite reports in China, and then in late 1941 the arrival of the American Volunteer Group, it was still believed that the Western aircraft were superior to their Japanese counterparts.
So the shock of the Japanese assault on December 7/8, 1941 (depending on which side of the International Date Line you were on) was unbelievable. The Japanese seemed to be everywhere at once; on the first day of the war alone, they attacked by sea, land or air all over the Pacific: Pearl Harbor, Manila, Midway, Hong Kong, Thailand, Shanghai, Wake, Guam, Singapore, Dutch East Indies, Malaya, and Burma. The Japanese Forces often enjoyed superior numbers and equipment as well as tactics and training, allowing them to move quickly across the Pacific.
Islands fell in rapid succession:
|December 8||The Foreign Quarter of Shanghai|
|December 25||Hong Kong|
|January 2||Manila, Philippines|
|January 25||Balikpapan, Java|
|February 14||Paratroops landed on the oil works on Palembang, Sumatra|
|February 19||Bombers from the First Air Fleet attack Port Darwin|
|March 5||Batavia, Java|
|March 20||The occupation of Admiralty and Western Solomons complete|
|April 8||Rangoon, Burma|
|May 9||Corrigedor fell, ending all resistance in the Philippines|