Under the aegis of the K-Verband (Kleinkampfmittel-Verbande) small battle units, experiments with the BIBER (pronounced bEEber, means beaver), one-man submarine, were carried out to determine the feasibility of using the TYPE VII-C U-Boat to carry the short ranged BIBERs to distant targets. Trials held in the Baltic showed that a TYPE VII-C could carry two BIBERs (one forward and one aft) and launch them into the open sea.

Operation CAESAR was the one and only time that this technique was tried operationally. Training for the operation began for the BIBER boats of K-Flotille 265 at Harstadt, Norway in November 1944. Six BIBERs were loaded on 3 TYPE VII-C boats. They were U-295 (Kplt GCinter Wieboldt), U-716 (Oblt Rirgen Thimme) and U-739 (Oblt H-J Schild). Each U-Boat was equipped with deck clamps to carry their assigned BIBERs. The BIBERs were freed from their deck positions by unlocking the clamps, and the mother boat submerged beneath them for the attack to commence.

It had been originally planned for the midgets to be released some 40 miles from the target area, in mid-afternoon. Each BIBER would then spend some 12 hours in penetrating the Kola Inlet, choosing targets for each of their two G7e electric torpedoes, prior to first light. Following their attack, they would be guided by acoustic signals back to the mother boats which would by now be lying some 4 miles offshore, who would take off each BIBER pilot and scuttle the craft.

The three U-Boats with midgets aboard, left Harstadt for the Kola peninsula on January 5, 1945. They still scheduled for 8 January, with the object of attacking the shipping there, particularly the Soviet battleship ARCHANGELSK (ex HMS ROYAL SOVEREIGN) based at Murmansk.

The generally poor condition of the BIBERs however, proved the mission's undoing when it was discovered that the continual vibration of the U-Boat diesels on the high-speed surface run to the Kola area, had caused multiple structural failures to the BIBERs such as rupturing gas lines to the Opel Blitz truck engines and opening watertight seals.

Every effort was made to patch up the damage, but the serious structural damage forced the abandonment of Operation CAESAR on January 8.

Biber: German Midget Submarines