The Battle of Pierres Noires was a naval action that occurred during the Allied Operation Dredger, involving several Royal Canadian Navy destroyers and a Kriegsmarine u-boat with escorts near Brest, France. The RCN force managed to sink or damage some of the escorts on the surface, but the U-boat was able to escape.
The port of Brest had been an important U-boat base since the Fall of France, and its capture was one of the objectives of Operation Overlord. With the increasing effectiveness of the Allied anti-submarine campaign however it often became essential for any U-boat departing the port to have surface escorts. The Kriegsmarine would often employ Vorpostenboot class escort trawlers to accomplish that task, and over time these boats developed a fearsome reputation among the Allied navies. On July 5, 1944 Escort Group 12 and Escort Group 14 were deployed to the vicinity of Brest as part of Operation Dredger; EG 12 (Consisting of the RCN River-class destroyers HMCS Saskatchewan, HMCS Qu'Appelle, HMCS Skeena and HMCS Restigouche) was tasked with intercepting the ships escorting the u-boats, while EG 14 would patrol further offshore to intercept any U-boats that managed to escape.
U-741 departed Brest on 5 July 1944 under the protection of 4 Vorpostenboot escort trawlers. Escort Group 12, with HMCS Qu'Appelle as the lead boat, detected the German force on radar and set off in pursuit at 30 knots. The two sides engaged in the vicinity of the Pierres Noires lighthouse in the late evening. The darkness, combined with uncertainty of the size of the German force and the close range at which the ships engaged each other nullified some of the advantage in speed and armour enjoyed by EG 12, and U-741 managed to escape. However, despite inflicting some damage to all of the Canadian vessels, the Vorpostenboot V-715 was sunk, another was heavily damaged, and the remainder withdrew to Brest. EG 12 withdrew to Portsmouth for repairs.
Operation Dredger would continue with further Allied naval infiltration into the Bay of Biscay, engaging the U-boats and their escorts in their home waters. U-741 was sunk in the English Channel on 15 August, a few days after American forces began to lay siege to Brest. The last U-boat departed on 4 September, just before the Americans took control of the city on September 19. HMCS Skeena would be lost in a storm off Iceland on 25 October, the only ship from EG 12 not to survive the war.