Beginning in the early 1920's, the German Navy developed an extensive marine mine research program, and by the outbreak of World War II possessed a number of revolutio-nary types ready for mass production. These included seven contact mines, eight influ-ence mine cases, and three magnetic units. Among them were ground and moored mines suitable for laying by aircraft, surface vessels, and submarines.

The German Navy had already perfected highly effective contact mines during the first World War, but Allied countermeasures seriously limited their effectivenses. Conse-quently, in 1922, research began upon mines operating on non-contact principles, and was first directed toward the development of a magnetic mine.