Final answer:
American General Douglas MacArthur led the successful US occupation of Japan from 1945 to 1952, which resulted in significant political and military reforms and transformed Japan into a democratic nation in alliance with the US.
Step-by-step explanation:
General Douglas MacArthur was the American general who led the US occupation of Japan, overseeing profound changes in Japanese government, society, and military policy, and laying the foundations for Japan's post-war recovery and democratic governance.
The United States, under the leadership of MacArthur, occupied Japan from 1945 to 1952. During this period, the occupation focused on demilitarization, democratization, and the promotion of human rights. Political changes included the implementation of a new Japanese constitution and the dismantling of Japan's military capabilities. MacArthur also worked to foster economic recovery, setting Japan on a path to becoming a prosperous democracy. The success of the occupation is reflected in the fact that Japan has remained a peaceful ally of the United States, retaining the key reforms that were introduced during this period of transformative change.