The S-Boot class 1939/1940 was the largest class of fast attack boats built in Germany during World War II. These boats were modified based on wartime experience, including a tripling of their light flak armament in later models. Powered by Daimler Benz diesel engines, they could reach speeds over 40 knots. From S100 onwards, the boats were equipped with armored control platforms to protect the crew. Most of the over 100 boats built were lost during the war. Surviving boats were given to various countries after the war, including the Soviet Union, Norway, and Denmark. Some were later returned to the German Bundesmarine for experimental purposes.