On the evening of 23 June 1944, HMCS Haida and HMS Eskimo set out from Plymouth, operational base of the 10th Destroyer Flotilla (10th DF), to conduct a sweep of the Western Approaches to the English Channel. Their role was to assist in securing these waters for the ongoing delivery of supplies and reinforcements to the Normandy bridgehead. Across the Channel to the southest, American, British and Canadian forces were now in their third week of fighting across the fields and hedgerows of Normandy. Operation OVERLORD had been the largest amphibious invasion in history and, dependent as it was on the unimpeded use of the sea, required an intensive concentration of air and naval forces to protect Allied supply convoys. This naval counterpart of OVERLORD was Operation NEPTUNE, and it was as part of this massive undertaken that Haida and Eskimo now steamed out of Plymouth.
Gough, Barry M. and Woods, James A. "“One More for Luck”: The Destruction of U971 by HMCS Haida and HMS Eskimo, 24 June 1944." Canadian Military History 10, 3 (2001)