The Battle of the Atlantic, 1941-1943: Peaks and Troughs
The westward extension of U-boat operations had necessitated the stationing of a German tanker to the southwest of Greenland; other ships were at sea to provide middle and South Atlantic replenishment for submarines and raiders. The most unlooked-for reprieve came from Hitler himself when, early in September, he ordered six of the Atlantic U-boats to the Mediterranean, where the war at sea was going badly for the Axis. The numbers available for Atlantic operations were made up by new arrivals from German home waters, but this meant that the defenses faced no more submarines in October than they had in the two preceding months, while their own strength continued to increase. The Operational Intelligence Centre was aware of the Mediterranean reinforcement and of the general abandonment of the Atlantic, and it took appropriate steps not merely to protect shipping but also to sink U-boats.