At the age of 29, Flettner presented his first invention, a steerable torpedo, to the Kriegsmarine (German Imperial Navy) of World War I.[1] This, and his next invention, a remote-controlled combat car, which was presented to the Heer (German Army), were rejected because they were not considered to be technically feasible.[2] However, Flettner's efforts culminated in the prototype Siemens Schuckert Werke 1000 kg wire guided air to surface missile of 1918.[2]