SC 2 was opposed by a patrol line of three U-boats, positioned at the limit of endurance to intercept east-bound convoys before the Western Approaches escort had joined.

U-boat Command (BdU) had been informed of SC 2's passage by B-Dienst, the German signals intelligence branch, which had cracked the Royal Navy's codes.

In the early hours of 7 September U-47 made a series of attacks, and succeeded in sinking three ships, the freighters Neptunian, Jose de Larrinaga and the Norwegian, Gro.

U-47 continued to shadow but was unable to mount a further attack until the night of 8/9 September when she sank the Greek freighter Possidon, at a point west of the Hebrides.

Previous attempts to form wolf packs, with control exercised at sea by a senior U-boat commander, had met with failure.