"He began his career in the Imperial German Navy before World War I. In 1918, he was commanding UB-68 when she was sunk by British forces. ...
Dönitz was taken prisoner. While in a prisoner of war camp, he formulated what he later called Rudeltaktik ("pack tactic", commonly called "wolfpack").
At the start of World War II, he was the senior submarine officer in the Kriegsmarine, known as Befehlshaber der Unterseeboote (BdU). In January 1943, Dönitz achieved the rank of Großadmiral (grand admiral) and replaced Grand Admiral Erich Raeder as Commander-in-Chief of the Navy. Dönitz was the main enemy of Allied naval forces in the Battle of the Atlantic. From 1939–1943 the U-boats fought effectively but lost the initiative from May 1943. Dönitz ordered his submarines into battle until 1945 to relieve the pressure on other branches of the Wehrmacht (Nazi German Armed Force). 648 U-boats were lost—429 with no survivors. A further 215 were lost on their first patrol. Around 30,000 of the 40,000 men to serve on U-boats perished." - (en.wikipedia.org 30.01.2020)
