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All I could find, hope it helps.

In October 1941, Hitler ordered Dönitz to move U-boats into the Mediterranean to support German operations in that theatre. The resulting concentration near Gibraltar resulted in a series of battles around the Gibraltar and Sierra Leone convoys. In December 1941, Convoy HG 76 sailed, escorted by the 36th Escort Group of two sloops and six corvettes under Captain Frederic John Walker, reinforced by the first of the new escort carriers, HMS Audacity and three destroyers from Gibraltar. The convoy was immediately intercepted by the waiting U-boat pack, resulting in a brutal battle. Walker was a tactical innovator, his ships' crews were highly trained and the presence of an escort carrier meant that the U-boats were frequently sighted and forced to dive before they could get close to the convoy. Over the next five days, five U-boats were sunk (four by Walker's group), despite the loss of the Audacity after two days. The British lost the Audacity, a destroyer and just two merchant ships. The battle was the first clear Allied convoy victory.
Through dogged effort, the Allies slowly gained the upper hand until the end of 1941. Although Allied warships failed to sink U-boats in large numbers, most convoys evaded attack completely. Shipping losses were high, but manageable.