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
45th Airlift Squadron February 1944 until becoming part of IX Troop Carrier Command in England to participate in the buildup of forces prior to the Allied landings in France during D-Day in June 1944. Engaged in combat operations by dropping paratroops into Normandy near Ste-Mere-Eglise on D-Day, 6 June 1944, and releasing gliders with reinforcements on the following day. The unit received a third Distinguished Unit Citation and a French citation for these missions. After the Normandy invasion the squadron ferried supplies in the United Kingdom. The squadron also hauled food, clothing, medicine, gasoline, ordnance equipment, and other supplies to the front lines