Adolf Hitler orders "Plan Z"

Plan Z was the name given to the planned re-equipment and expansion of the Nazi German Navy (Kriegsmarine) ordered by Adolf Hitler on January 27, 1939.

The plan called for a Kriegsmarine of ten battleships, four aircraft carriers, three battlecruisers, eight heavy cruisers, 44 light cruisers, 68 destroyers and 249 U-boats by 1944 that was meant to challenge the naval power of the United Kingdom.

Following the end of World War I, the German armed forces became subject to the stipulations of the Treaty of Versailles. For the navy, this meant it was restricted to six armoured warships ("panzerschiffe"), six cruisers, twelve destroyers and twelve torpedo-boats. With the scuttling of the majority of the High Seas Fleet at Scapa Flow, new construction was needed. The first major ship to be built after the war was the light cruiser Emden. This was followed by a further three light cruisers of the K class; Königsberg, Karlsruhe and Köln, and a further two ships that were modified versions of the K class, Leipzig and Nürnberg.

Changes in technology, especially power plants, re-invigorated the panzerschiff concept, primarily for commerce raiding, allowing the Germans to build ships that evaded the provisions of the Treaty of Versailles on capital ship construction, while being smaller, better armored and still faster than their World War I counterparts. The new designs were widely lauded around the world. Designed as they were to implement the envisaged likely German war strategy of commerce raiding while avoiding engagements with heavy capital ships, no other major naval power with their different strategies and needs copied them. The British with their dependence on seaborne trade did not require commerce raiders. Their needs were for commerce protection, and built warships suitable for that task. Other major navies did likewise.