The History of the German mini-submarines (Kleinkampfmittel) is the one of another desperate attempt to prevent the final outcome of the war. While other nations like Britain and Italy used such vessels in successful in special operations, their German counterparts were unable to archive similar results.
Used between early summer of 1944 and the end of the war, those small vessels were a kind of last line of defense at the shorelines and had to operate against advanced allied anti-submarine forces at the French invasion coast. While the early developments even were unable to dive, the last developments showed some quite advanced boats, but caused by the very short development times, none of them was flawless. Only with the appearance of the Seehund
, the first really operational vessel was designed, but at this time (spring of 1945) their use was against all odds.
Besides the designs on this page - which were all build in high numbers - several other prototypes and studies, like boats that could drive on the sea ground were made, but none of these never got operational