All of the major naval powers of World War 2 (1939-1945) utilized some sort of submersible "midget" submarine. These midget submarines were just that, smaller versions of their full-size brethren intended to sneak past traditional naval defenses to wreak havoc on unsuspecting targets - particularly while the targets lay berthed and highly vulnerable. One such German attempt became the "Biber" ("Beaver") which was delivered across some 324 examples. Despite their numbers, their true effect on the war was very minimal with their contribution largely forgotten today.
As designed, the Biber displaced 6.3 tons (short) with a running length of 29 feet, beam of 5 feet, 3 inches and draught of 5 feet, 3 inches. These compact dimensions ensured that the vessel could traverse even the most shallow of harbors in seeking out a potential target. Surface power was through an Otto gasoline engine of 32 horsepower with undersea power granted by 1 x electric motor generating 13 horsepower. The crew was just one operator and armament being 2 x TIIIc series torpedoes. This could be replaced by a pair of naval mines as required. The vessel could make headway at 6.5 knots when surfaced and 5 knots submerged. Range was out to 100 nautical miles during surface travel with a reachable depth of 20 meters being reported for undersea work.
The Biber was developed particularly in response to the Allied footholds being gain in Europe, first through the Italian landings and then culminating with the landings at northern France. In order to feed, clothe and resupply Allied elements on the European mainland, waterways accessing the French, Italian, and Low Country shores would become critical to Allied success in the European campaign as a whole. The Biber was thusly hurried into operational service and this no doubt showcased errors in its design.
The initial Biber prototype was completed in March of 1944 over the span of six short weeks. Testing then occurred in May to which the German Kriegsmarine contracted for twenty-four specimens. Finalized operational forms were two meters longer than the prototype with other subtle changes added.
With the Allied advance a realized threat now, training of Biber operators were hastened, leading to poorly trained crews. Biber practical use was limited when scanning and tracking surface vessels and there proved no night-vision assist. First notable operations involving Bibers occurred in December of 1944 near Terneuzen in which eighteen boats were committed to a sortie. This resulted in the sinking of the USS Alan A. Dale cargo ship and only a single Biber submarine managed to return home. More mysterious operational losses occurred thereafter, proving the dangerous nature of a one-man submarine with limited resources in dark water. The final mission involving Bider submarines was an attempt to sink the Soviet battleship Arkhangelsk, which was not in Vaenga Bay port at the time, and any shipping targets of opportunity. The mission was scratched when the Bibers took on water while being carried by accompanying U-boat motherships.