Southwick House: Inside the countryside home where the D-Day Landings were planned. How to visit the map room

Southwick House was chosen to be the headquarters of the Supreme Allied Commander General Dwight Eisenhower, with its location close to Portsmouth and Fort Southwick making it perfect to gather and plan what was to be Operation Overlord, the codename for the Battle of Normandy.

A giant map was set up to plot the movements of the convoys across the Channel and deep underground tunnels of Fort Southwick – where much of the data was gathered and analysed - also linked up to Southwick House to ensure the efforts between the two locations were fully coordinated.

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In the days prior to the invasion, General Eisenhower was visited by Winston Churchill and General Charles de Gaulle of France. The decision to launch D-Day was delayed by 24 hours because of awful weather before Eisenhower announced his decision in the library with the famous words: “Okay, let’s go.”

A 1,200-plane airborne assault preceded an amphibious assault involving more than 5,000 vessels and nearly 160,000 troops crossed the English Channel on 6 June 1944, and more than two million Allied troops were in France by the end of August making it the turning point of the Allied war effort.

Watch the video embedded in this story to hear from Richard Callaghan, curator of the Royal Military Police Museum at Southwick, explain more about the role of Southwick House.

You can visit the map room by appointment only. For more details call 023 9228 4341.