The Kriegsmarine (German: War Navy) was the name of the German Navy from 1935 to 1945, the Commander-in-Chief of which was Adolf Hitler. It was was one of three official branches of the Wehrmacht or the armed forces of Nazi Germany.
Even before the Nazi take over of the German government in 1933 it had been decided to reinvigorate the navy with U-boats, planes and ships. This had been specifically banned by the Treaty of Versailles, an agreement by which Germany was forced to accept responsibility for causing the First World War, make territorial concessions, pay reparations to certain countries and most importantly to disarm.
Once Adolf Hitler came to power he accelerated this naval rearmament and the Kriegsmarine grew rapidly. However, its absolute size, outlined in the so-called Plan Z, was held back as substantial amounts of resources were diverted to other war preparations. As a consequence the German Navy was still at a disadvantage at the start of Second World War in terms of its size compared to the combined navies of France and Great Britain, its main antagonists.
The Kriegsmarine’s most famous ‘boats’ were the U-boats, most of which were constructed at the beginning of World War II. Collections of U-boats formed “Wolf Packs” which successfully attacked British convoys during the first half of the Battle of the Atlantic. (Their most famous ‘ships’ were arguably the battleships Bismark and Tripitz).
However, by the end of 1944 the fortunes of submarine warfare had changed due to the development of radar, longer range air cover, sonar, improved tactics and new weapons and a desperate Kriegsmarine formed the Kleinkampfverbände (Small Battle Units) to fight the Western Allies. One of the more effective of these battle units were the midget submarines such as the Seehund.
After the end of the Second World War, the Kriegsmarine remaining ships were divided up amongst the Allied powers and were used for various purposes including minesweeping.