Code-named Rossbach, the group was stationed at the western edge of the Greenland Air Gap to intercept the expected east-bound convoys, carrying materiel for the invasion of Europe.

While forming, Rossbach came under attack by air patrols; four boats were destroyed, and another four were damaged and forced to return to base.

By 6 October Rossbach, comprising fourteen U-boats at this point, was deployed to intercept the expected west-bound convoys, HX 259 and SC 143.

Western Approaches Command became aware of Rossbach's position via intelligence, principally Enigma decrypts, but decided to engage the wolfpack and force a battle.

Diverting HX 259 to the south, SC 143 was reinforced with 10th Support Group, of four destroyers, Musketeer, Oribi, Orkan and Orwell, and allowed to continue towards Rossbach as bait.