Victory over Japan Day (also known as Victory in the Pacific Day, V-J Day, or V-P Day) is a name chosen for the day on which the Surrender of Japan occurred, effectively ending World War II, and subsequent anniversaries of that event. The term has been applied to both the day on which the initial announcement of Japan's surrender was made in the afternoon of August 15, 1945, in Japan, and because of time zone differences, to August 14, 1945, (when it was announced in the United States, Western Europe, the Americas, the Pacific Islands, and Australia), as well as to September 2, 1945, when the signing of the surrender document occurred.
Also See:
http://wb9otx.blogspot.com/2010/08/vj-day-august-15-1945.html
