The crew left on shore leave, which lasted still longer after a Lancaster bomber sent to destroy the submarine dropped a Tallyboy bomb on that pen-cryptographers at Bletchley Park had already learned of the plan.
The crew left on shore leave, which lasted longer than expected after the pens and shipping in the harbour were attacked on 12 January by 32 Royal Air Force Lancaster bombers and one Mosquito bomber of Numbers 9 and 617 Squadrons. Cryptographers at Bletchley Park had already learned of the plan.