Hitler was highly impressed by Doenitz' talent, and appointed him Commander in Chief of the Navy in January '43. However, this personal triumph nearly coincided with the beginning of the end for his U-boats, in the "Battle of the Atlantic". The Allies, having learned the hard way, had built the large numbers of destroyer escorts, corvettes and anti-submarine patrol bombers needed to guard their convoys. They had found the correct tactics to counter the wolf-packs and had become proficient through many months of practical experience. New Allied weapons, like RADAR or the escort carrier, more than matched new German innovations like the Schnorkel. BUT most important, they were building new cargo ships faster than the U-boats could sink them, and if that was true, there was no way the U-boats could win, because their objective in the Battle of the Atlantic wasn't to sink ships, it was to starve Britain! Although the Allies were clearly ahead by the summer of 1943, Hitler continued to respect Doenitz' skill, and he seems to have done so to the very end. For whatever reason, Hitler named Doenitz to succeed him, just before killing himself. Thus Doenitz became the last ruler of Nazi Germany, for a little over one week.
After the surrender, Doenitz was tried for War Crimes at Nuremburg. He succeeded in convincing the tribunal that he had been kept ignorant of the murder of millions in the Concentration Camps and Death Camps of "the final solution", but was sentenced to ten years for "Planning Agressive War". [ Author's Note: It may seem unbelievable that anyone in Germany, let alone a highly placed leader like Doenitz, was not aware of the murder of six million people being carried out around him. However, I have spoken to an Allied Intelligence Officer who was in Europe during the war, and present as one of the official Interrogators for the Nuremburg Trials, who believes the evidence supports Doenitz' story. There was an organized deception program designed to convince anyone (who could not simply be silenced) that the Concentration Camps were just big prisons and any rumors one heard about mass murder were only "Allied lies". Doenitz' claim to have been taken in by this operation seems plausible to the intelligence officer, because, he says, HE was taken in by it himself, even though as an American, he had less reason to believe the Nazis than Doenitz did! - DAW ]