During 1943, No. 461 Squadron mainly conducted daylight anti-submarine patrols over the Bay of Biscay, having moved to a new base at Pembroke Dock in April 1943. These patrols exposed the squadron's aircraft to frequent attacks by German fighters. The Sunderland aircraft were fitted with a heavy defensive armament, however, and were often successful in beating off fighter attacks. During 1943, the squadron sank a total of three U-boats. By May 1943, No. 461 Squadron was fully equipped with the more advanced Mark III Sunderland. This aircraft allowed the Squadron to operate at night. Equipped with these improved aircraft the squadron continued to fly anti-submarine patrols over the Atlantic, including patrols in support of the Allied landing in Normandy. The squadron sank three U-boats during 1944.