At the outbreak of the Second World War Nazi Germany's Kriegsmarine had 21 destroyers (Ger: Zerstörer) in service, while another one was just being completed. These 22 vessels – comprising 3 classes (Type 34, 34A and 36) – had all been built in the 1930s, making them modern vessels (no destroyers remained in German hands following the close of the First World War). Including that final pre-war vessel, a further 19 were brought into service during the war and more were captured from opposing navies, including the Italian Navy (Regia Marina) after the Italian Armistice with the Allies in 1943. German destroyer classes were generally known by the year of their design. Because of their size, use and weaponry, some vessels classified as "fleet torpedo boats", Flottentorpedoboot, are also described as destroyers. During World War II, destroyers were administratively grouped into one of several destroyer flotillas. Class general characteristics are taken from the first of each class, and may differ slightly for individual ships, particularly when they were refitted. Post-war, some surviving ships had significant changes to armament. Zerstörer 1934 This class of four ships was the first German destroyer class. It was designed around a new type of engine, using high pressure steam. This should have allowed higher speed, while saving space and crewmembers. The engine was however so complicated and prone to breakdown, that it forced the navy to assign even more very highly qualified personnel on board to operate and service them. As a result of stability problems, the range of the ships had to be restricted by navy regulations, allowing them to use only half of the fuel carried, to prevent the ships from becoming too light. The bow proved to be of faulty design, resulting in the ships being rather wet in heavy seas. This was fixed by rebuilding all four ship of the class before 1939. Four destroyers were laid down between October 1934 and January 1935. Only one ship survived the war. The ships were named after German navy personnel killed in World War I. The ships were: Zerstörer 1934A Twelve destroyers laid down between July and November 1935. They were only slightly modified from the design of the preceding 1934 class and continued their predecessors' limited endurance and magazine capacity – factors which contributed to the heavy German losses in the Second Battle of Narvik. Five survived the war. Zerstörer 1936 These