Many look with amazement at the rebirth of the nation of Japan from the ashes of World War II. This is a study of the postwar military government and administration of Japan. It will examine the detailed preparation, the initial objectives, and the execution of the occupation by the United States (US)-led forces. The military government and civil affairs doctrine used, will be analyzed. The lessons gained from this study should be useful to the expeditionary army today. The military government teams that executed the policies of the occupation at the prefecture level will be a focus of this study. This study will provide insights into what made the occupation of Japan, 1945-1950, so successful. The lasting peace and prosperity of modern-day Japan makes this endeavor, by the US and her Allies, worthy of renewed study and possible application today.