Admiral Karl Doenitz was the leader (Befehlshaber der Unterseeboote) of the Nazi U-boot campaign during World War II. Under his administration, the U-boat fleet came very close to starving the United Kingdom of vital supply shipments from the United States. During 1943 the war in the Atlantic turned against the Germans, but Doenitz continued to push for more U-boat construction and technological development. At the end of the war the Nazi submarine fleet was by far the most advanced in the world, and late war examples such as the Type XXI served as models for Soviet and American construction after the war.
Doenitz was also chosen by Adolf Hitler as his successor, a choice that shows how distrustful Hitler had become of Goering and Himmler in the final days of the War in Europe. After Hitler committed suicide on April 30 1945, Doenitz became the final German Fuehrer, ruling until the final surrender on May 8. He devoted most of his efforts to trying to ensure that German troops surrended to the Americans and not the Soviets, since the Germans feared that the Soviets would torture or kill them in revenge for how they had treated the Soviets.