During the Second World War much of the Allied planning for operations was conducted in London. The plans for Operation Overlord (D-Day) were finalised at Southwick House in Hampshire. This became the headquarters of the main Allied commanders, led by General Eisenhower. The whole of the village was taken over by the Allied command.

As the Embarkation Area Headquarters for the Portsmouth sector during the D-Day campaign, Quay House was central to the successful launching of the campaign. Organising the launches of the allied troops from four areas across Portsmouth to the beaches of Normandy, France, military personnel at Quay House played a vital role in ensuring the campaign ran efficiently.

The Royal Naval Hospital Haslar was a key site for the treatment of soldiers returning from Normandy, injured in action during D-Day and in subsequent fighting. Run by the United States Military during 1944 and 1945, the staff treated both Allied soldiers and German prisoners of war, before they were transferred to other hospitals around Britain.

Re-opened in April 2018, the D-Day Story takes the visitors through the build up to the event, D-Day itself and the Battle of Normandy. The story is told through the perspectives of the people involved using objects, interactives and video. The impressive 83-metre long Overlord Embroidery offers a fantastic finale to the visit.

The HMS Belfast warship is a floating museum which was originally a Royal Navy light cruiser. It became a branch of the Imperial War Museum in 1978. The ship is permanently moored on the Thames river next to Tower Bridge. The museum tells the personal stories of the crew who lived and served on board during the Second World War.