HMNB Portsmouth the military and naval units destined for Sword Beach on the Normandy coast as a part of Operation Overlord and the D-Day landings on 6 June 1944. Troops destined for each of the landing beaches left from Portsmouth aboard vessels such as the armed merchant cruisers HMCS "Prince Henry" and HMCS "Prince David", escorted by the Canadian destroyers HMCS "Algonquin" and "Sioux". The majority of the naval support for the operation left from Portsmouth, including the Mulberry Harbours. Boathouse 4 (built around the start of hostilities) contributed to the construction of landing craft and support vessels as well as more
Australian contribution to the Battle of Normandy D-Day landings, it is not possible to determine the exact number involved. However, it has been estimated that about 3,000 Australian military personnel and merchant seamen participated in the operation. The total number of Australians killed on 6 June was 14, of whom 12 were RAAF airmen and two were members of the RAN. The fighting in Normandy continued until August 1944, when the Allies broke out of the region and rapidly advanced to the German border. This campaign dominated the activities of eight of the ten Australian squadrons in the UK, as well as most of the airmen posted