'Grube' was the U-boat wolfpack operation in the Arctic Ocean against the passage of the JW.62 convoy supported by 'Golden' (November/December 1944).
Stationed off the Kola inlet, the wolfpack comprised U-295, U-310, U-387, U-668, U-965, U-997 and U-1163, and neither lost any of its own number nor sank any ship.