Answer: Admiral Hyman G. Rickover
Hyman George Rickover was born in Russian-occupied Poland on January 27, 1900. The son of poor Jewish parents, he emigrated to the United States at age five, along with his parents, and grew up in Chicago. He earned an appointment to the United States Naval Academy in 1918, and was graduated in 1922. He served on a variety of ships; in 1929 he became qualified in submarines. During WWII he served as the head of the Electrical Section in the Bureau of ships. In 1949 he became Director of Naval Reactors, and oversaw the development of the first pressurized water reactor.
Rickover was a very difficult man to get along with, and was frequently involved in disputes with other officers, as well as the civilian contractors who built the Navy's ships. But he continued to serve until 1982, when he was forced to retire as a full Admiral by Secretary of the Navy John Lehman, a former aviator who knew nothing about submarines or nuclear power. His 63 years of continuous active service make him the longest serving officer in United States military history. Rickover died July 8, 1986 and is buried in Arlington National Cemetery.