Karl Dönitz was born September 16th, 1891 in Grünau, at the time a small town near Berlin and today a suburb of the German capital. His father was Emil Dönitz and his mother Anna Beyer. Karl had an elder brother Friedrich. In April 1910, Karl joined the Kaiserliche Marine (Imperial Navy) and he entered service as Seekadett (midshipman). Hardly a year later, on April 15th, 1911 he was promoted to Fähnrich zur See (ensign). At the age of 22, Karl Dönitz received his commission as officer, holding the rank of Leutnant zur See (Lieutenant 3rd classs).
In World War One, Karl Dönitz served aboard the light cruiser Breslau of the Magdeburg class. He rose quickly throught the ranks and was promoted to Oberleutnant zur See (Lieutenant 2nd class) on March 22nd, 1916. On May 27th, that year he married the nurse Ingeborg Weber, daughter of a general. Shortly afterwards he applied for a transfer to the submarine service. His request was granted in October 1916 with his posting as officer of the watch aboard U-39. On April 3rd, their daughter Ursula was born. In February 1918 he was appointed commander of UC-25 and on July 2nd of that year he took command of UB-68. He saw action in the Mediterranean in this submarine. On October 4th, 1918, UB-68 was forced to surface due to technical problems and the vessel was sunk by British gunfire. Dönitz and 32 members of his crew survived the sinking and were imprisoned in Valetta on Malta. After the armistice in November 1918, Dönitz was held as a prisoner of war in a camp near Sheffield in Great Britain. His release was accelerated for medical reasons and he returned to Germany in July 1919. On May 14th, 1920, son Klaus was born.
Oberleutnant zur See Dönitz continued his career in the Vorläufige Reichsmarine (temporary state navy), which had evolved out of the Kaiserliche Marine as the naval branch of the Reichswehr of the Weimar Republic. On January 10th, 1912, within a year, he was promted to Kapitänleutnant (Lieutenant 2nd class senior grade). On March 20th, 1922, the Dönitz family was enlarged by the birth of son Peter. The following years, Dönitz was mainly active as commander of various torpedoboats until November 1st , 1928 when he was promoted to Korvettenkapitän (Lieutenant 1st class). The same day he took command of 4.Torpedobootshalbflotille consisiting of the brand new torpedoboats Albatros, Kondor, Möwe and Greif.
The naval officer from Grünau continued to rise and on September 1st, 1933, he was sworn in as Fregattenkapitän. Like many other German officers, Dönitz was frustrated by the downfall of the German Empire and the degeneration of the German navy. He yearned for restoration of order and a new leader. In 1933 he joined the Nazi party (N.S.D.A.P. ) because he considered Hitler the man who could transform Germany into a global empire again. In 1934 he took command of the light cruiser Emden and made a tour around the world showing the flag with this vessel that lasted a year. On board there were many cadetts and ensigns who could gain practical experience on this trip. In 1935, the Reichsmarine of the Weimar Republic was blended in with the Kriegsmarine of Nazi Germany. September 1st of the same year saw Dönitz being promoted to Kapitän zur See and commander of 1. U-bootflotille Weddingen, consisting of U-7, U-8 and U-9.
Just like all other navies of the world at the time, the Kriegsmarine saw its submarine arm as part of a surface fleet that was to be deployed against enemy warships, in Germany’s case mainly British and French naval units. Karl Dönitz openly argued for a German war fleet which was to consist mainly of U-boats. These boats should concentrate on British and French merchant shipping and oil tankers. These were relatively easy targets and by destroying the enemy’s merchant fleet, the war fleet would be crippled owing to lack of fuel and provisions. He claimed he could bring the enemy to its knees with a fleet of 300 new U-boats Type VII.
During his imprisonment in Wold War One, he had devised the strategy of the Wolfpack where a number of U-boats simultaneously attacked merchantmen and their escorts. In this period this was not yet possible as the German U-boats did not have the right communication equipment at their disposal. Halfway through the 30s however, the Germans had developed ultra high frequency (UHF) radioequipment and messages could be encrypted by the new Enigma machine.
Kapitän zur See Dönitz stood alone though with his ideas and he was hardly taken seriously by the other German naval officers. He had a ongoing quarrel with the Commander-in-Chief of the Kriegsmarine, Erich Raeder (Bio Raeder) who advocated a larger surface fleet. Owing to the limitations on shipbuilding in the Treaty Of Versailles, Germany only had a small number of modern surface units available that would surely lose the battle against the superior British and French warships. Raeder however counted on Plan Z, the expansion of the High Sea fleet but this construction programme would only be completed in 1945. On January 28th, 1938, Karl Dönitz was promoted to Führer der Unterseeboote (chief of the submarine arm) in the rank of Kommodore (Commodore). In 1939, Karl Dönitz wrote a book about his plans and ideas. Apart from tactics and strategies, he also desribed his Nazi fanatism and his appreciation for the camaradery among the U-boat crews.