The Biber was one of the weapon systems developed during the Second World War at the time when the situation on both fronts was gradually becoming worse and worse for Germany. In 1943 it became clear that the Allied invasion would take place soon somewhere on the Atlantic coast of the continent and the German military began to seek and develop new and rather unorthodox weapons to avert the invasion. Along the Neger, Marder and Hai manned torpedoes, also the Biber and Molch midget submarines were to stop the invasion fleet.
The original idea of the Biber sub came from Korvettenkapitn Robert Bartels and first prototypes were built and the production took place at Flanderwerke in Lbeck, the development being led by Hermann Bunte. Allegedly, Bartels was influenced by captured British Welman W46 midget sub. The Bibers displacement was 6.6 tonnes, on the surface it was powered by a 32 HP Otto Blitz petrol engine and while submerged, the propulsion was provided by a Siemens SSW GL231 electric motor. The Biber could submerge down to 20m, in emergency to 30m. It could carry either two G7e torpedoes or mines. The hull was so diminutive that its operator (only a crew of one was possible) did not have much space in the conning tower.
The Biber prototype, known also as Adam, was put to tests on 29 March 1944, though the tests were not quite successful and several improvements had to be implemented before German admiral Karl Dnitz approved building of further four prototype Bibers and later also the large scale production, which gave a total of 324 Bibers from Flanderwerke, Ansaldo and Klkner-Humbolt-Deutz plants.
Bibers were put into so-called K-flottillen numbered 1 to 9, which saw action in the English Channel during the Allied invasion, in the North Sea off Norway, in the Scheldt estuary and also in the river Waal during the attack on the Nijmegen bridge. Bibers did not enjoy much success in the torpedo-carrying role, mine-laying missions suited them better. Some trouble also occured due to the exhaust fumes getting into the operators station and many Bibers were lost just to this reason. The conning tower lacked in height causing the submarine pilot, who was equipped only with wrist compass, difficulties in finding his way to the target. Moreover, the Biber although being rather manoeuvrable and stable on the surface, was clumsy while under the water. Several Biber submarines were captured during the war, but the Allies did not seem to find interest in them and tested them only very briefly. Some of the surviving machines have been put to display in museums.