Size US 12 24x23.5x13.5 mm 21.8x21.2 mm 

Kriegsmarine 48x32x7.5 mm 14x8x5 mm 13.32 g

The Kriegsmarine (German pronunciation: lit. 'War Navy') was the navy of Nazi Germany from 1935 to 1945. It superseded the Imperial German Navy of the German Empire (1871–1918) and the inter-war Reichsmarine (1919–1935) of the Weimar Republic. The Kriegsmarine was one of three official branches, along with the Heer and the Luftwaffe, of the Wehrmacht, the German armed forces from 1935 to 1945.

In violation of the Treaty of Versailles, the Kriegsmarine grew rapidly during German naval rearmament in the 1930s. The 1919 treaty had limited the size of the German navy and prohibited the building of submarines

Kriegsmarine ships were deployed to the waters around Spain during the Spanish Civil War (1936–1939) under the guise of enforcing non-intervention, but in reality supporting the Nationalists against the Spanish Republicans.

In January 1939, Plan Z, a massive shipbuilding program, was ordered, calling for surface naval parity with the British Royal Navy by 1944. When World War II broke out in September 1939, Plan Z was shelved in favour of a crash building program for submarines (U-boats) instead of capital surface warships, and land and air forces were given priority of strategic resources.

The Commander-in-Chief of the Kriegsmarine (as for all branches of the armed forces during the period of absolute Nazi power) was Adolf Hitler, who exercised his authority through the Oberkommando der Marine ('High Command of the Navy').

Among the Kriegsmarine's most significant ships were its U-boats, most of which were constructed after Plan Z was abandoned at the beginning of World War II. Wolfpacks were rapidly assembled groups of submarines which attacked British convoys during the first half of the Battle of the Atlantic, but this tactic was largely abandoned by May 1943, when U-boat losses mounted. Along with the U-boats, surface commerce raiders (including auxiliary cruisers) were used to disrupt Allied shipping in the early years of the war, the most famous of these being the heavy cruisers Admiral Graf Spee and Admiral Scheer and the battleship Bismarck. However, the adoption of convoy escorts, especially in the Atlantic, greatly reduced the effectiveness of surface commerce raiders against convoys.

Following the end of World War II in 1945, the Kriegsmarine's remaining ships were divided up among the Allied powers and were used for various purposes including minesweeping. Some were loaded with superfluous chemical weapons and scuttled.