List of heavy cruisers of Germany  The German navies of the 1920s through 1945—the Reichsmarine and later Kriegsmarine—built or planned a series of heavy cruisers starting in the late 1920s, initially classified as "Panzerschiffe" (armored ships). Four different designs—the , , , and es, comprising twenty-two ships in total—were prepared in the period, though only the three "Deutschland"-class ships and three of the five "Admiral Hipper"-class cruisers were ever built. The terms of the Treaty of Versailles, which ended World War I, limited German warships to a displacement of . The first class of ships designed under these restrictions was the "Deutschland" class, designed in the late 1920s, and commonly referred to as "pocket battleships". They incorporated a series of radical innovations to save weight, including extensive use of welded construction and diesel engines. An improved version, the D class, was planned for 1934, but escalating design requirements in response to the French s resulted in the replacement of the D class with the two s. Plans for an improved "Panzerschiff" were renewed in 1937 with the P class. Initially intended to comprise twelve ships, the P class was a central component of Grand Admiral Erich Raeder's Plan Z fleet, which was designed for a commerce war against Great Britain. Subsequent versions of Plan Z reduced the number of ships to eight and then removed them altogether, replacing them with the s by 1939. The five ships of the "Admiral Hipper" class were authorized under the terms of the Anglo-German Naval Agreement, signed in 1935, which permitted Germany of heavy cruisers. Of these ships, only three were completed; the outbreak of World War II in September 1939 caused work to be halted on the last two ships. In total, Germany completed six heavy cruisers, all of which saw extensive service with the fleet. The three "Deutschland"-class ships served on several non-intervention patrols during the Spanish Civil War in 1936–1938. Most of the heavy cruisers were used as commerce raiders during World War II, of which "Admiral Scheer" was the most successful; was scuttled after the Battle of the River Plate. was sunk by Norwegian coastal batteries during Operation "Weserübung", the German invasion of Denmark and Norway, just four days after the ship joined the fleet. , one of the two incomplete "Admiral Hipper"-class ships, was intended to be converted into an aircraft carrier, though the work was never completed. , the second unfinished ship, was sold to the Soviet Union, and subsequently shelled German soldiers advancing on Leningrad until German bombers sank her.