Japan experienced dramatic political and social transformation under the Allied occupation in 1945–1952. US General Douglas MacArthur, the Supreme Commander of Allied Powers, served as Japan's de facto leader and played a central role in implementing reforms. As the new de facto ruler of Japan, Douglas MacArthur ordered the drafting of a new constitution for Japan in February 1946. So great was his influence in Japan that he has been called the Gaijin Shōgun