Karl Dönitz was a German naval officer and politician, best known for his role as the commander of the U-boat fleet during World War II. He was born on September 16, 1891, and became an important figure in the Nazi regime, eventually succeeding Adolf Hitler as the head of state for a brief period in May 1945. After the war, Dönitz was tried at the Nuremberg Trials for war crimes, primarily for his involvement in unrestricted submarine warfare. He was sentenced to ten years in prison and released in 1956. Dönitz passed away on December 24, 1980.