This week in the war, on 12 January 1942, the U-123 sank the British steamer Cyclops near Cape Cod. The sinking marked the opening of Doenitz’s U-boat offensive in the western Atlantic—his so-called Operation ‘Drum Roll’ (Paukenschlag).

Before the end of January, German U-boats had sunk 40 merchant ships in the western Atlantic, from Newfoundland through the Caribbean to the Guianas in South America.

Much of the success was due to the deployment of the long range Type IX U-boats (as opposed to the older VIIs, which had shorter range).

For the U-boats, it was the start of the second ‘Happy Time’ of the Battle of the Atlantic. The time became happier still in February, when the U-boats added an additional rotor to their Enigma cipher machines. Britain’s Bletchley Park code breakers could no longer read the German messages.