The only two times Japan was ever successfully invaded by a foreign power occurred at Okinawa and Iwo Jima. In both cases, the invading power was the United States during World War II. Those islands were controlled by the Japanese, but invading American forces routed the Japanese under General MacArthur's island-hopping campaign in the Pacific theater. An interesting fact to note is that while the Americans invaded the Japanese, the Japanese also invaded US holdings among the Aleutian Islands in what is now Alaska.
