Following the St Nazaire Raid on 28 March 1942, Raeder decided the risk of further seaborne attack was high and relocated the western command centre for U-boats to the Château de Pignerolle, where a command bunker was built and from where all Enigma radio messages between German command and Atlantic based operational U-boats were transmitted/received. In July 1942, Hans-Rudolf Rösing was appointed as FdU West ("Führer der Unterseeboote West"). Pignerolle became his headquarters.