Operation Caesar

Location of U-864

Date	5 December 1944 - 9 February 1945
Location	North Sea
Result	British victory Operational failure

Belligerents

Germany

United Kingdom

Commanders and leaders

KKpt. Ralf-Reimar Wolfram †

Lt. James Launders

Strength

U-864 (Type IX U-boat)

HMS Venturer (V-class submarine)

Casualties and losses

Submarine sunk
All 73 crew killed

None

Operation Caesar was a secret mission carried out by Germany in World War II to supply Germany's faltering ally, Japan, with advanced technology to fuel their war machine. The operation was a complete failure.

The engagement that ended the mission is the only known instance in history of one submerged submarine sinking another submerged submarine.

On 5 December 1944, U-864, on her maiden voyage, was dispatched on a secret mission to deliver supplies to Japan. U-864's primary cargo was advanced Messerschmitt jet engine parts for use in Japanese aircraft and V-2 missile guidance systems. Her secondary cargo comprised 65 tonnes of the strategic material mercury in 1,857 canisters for use in weapons production.

She left Kiel and headed north. While going through the Kiel Canal, U-864 grounded and damaged her hull. Her captain, Ralf-Reimar Wolfram, decided to sail to the U-boat pens at Bergen, Norway. On 12 January 1945, while U-864 was still undergoing repairs, British bombers attacked the pens, delaying the repairs further. The repairs were completed in early February and Wolfram embarked on his mission once again. British code breakers at Bletchley Park deciphered Enigma encoded transmissions and were alerted to U-864's mission. To counter the German U-boat, the Admiralty diverted the submarine HMS Venturer, which had just left Lerwick in Scotland, to the coasts of Fedje, Norway to search for U-864.

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