Grand Admiral Karl Dönitz was commander of the U-boat fleet of the Kriegsmarine (German Navy) during the Second World War and very briefly leader of the remaining area of Nazi Germany upon Hitlers Death. Dönitz also served as a U-Boat captain during the First World War.
Upon the death of Hitler and Goebbels, Dönitz was appointed President. Dönitz immediately opened up negotiations with the Allied Powers to offer Germany's unconditional surrender. On May 7, the British and US governments accepted a surrender authorized by Dönitz. The decision was controversial, as the the Big Three Allied Powers had agreed not to accept any separate peace terms. Dönitz was subsequently arrested and tried as a war criminal.
Dönitz was placed on trial in Nürnberg where he was sentenced to ten years imprisonment for war crimes, largely related to his policy of unrestricted submarine warfare. A part of his defense at the trial was that the US had also waged unrestricted submarine warfare from day one of their involvement.
After his release he lived a quiet life writing a small number of books. His most famous being his memoir 10 Jahre, 20 Tage. 10 Years and 20 days; an allusion to his 10 years as a Kriegsmarine officer and his 20 days as the nominal head of the German state.