With plans for Operation Overlord already in motion in 1943, it was decid-ed that the advance command post of the Supreme Headquarters Allied Expeditionary Force would be at Southwick House, Hampshire. Here, the main Allied commanders would be close to both the ports from which the invasion would leave, and the troops which would lead the attack. Sir Bertram Ramsay, commander of the Allied naval effort, who already had his headquarters in the house, was joined in the months before D-Day by Allied Supreme Commander General Eisenhower and the Army Com-mander-in-Chief General Montgomery. The whole of the village was taken over by the Allied command, with Nissan huts erected to house the men and with the officer’s mess in the Golden Lion, a local pub. With inclement weather on the planned launch day, 5 June 1944, it was in the library of Southwick House that Eisenhower took the decision to postpone the invasion for 24 hours. Once a window of clear weather was identified, the order was given to commence Operation Overlord. After the invasion was launched, the operation was orchestrated from Southwick House, until early September 1944, when headquarters were moved to France. Inside the house a large plywood map was erected to plot the progress of Operation Neptune, the naval element of the invasion of occupied France. A small ladder was used by the Women’s Royal Navy Service stationed at the house to mark the positions of the naval forces each hour, and it was from this that commander Ramsay directed the operation. This map is still viewable at the house.   To visit Southwick House, please contact the Defence School of Policing and Guarding at DSPG-HQ-Information@mod.uk (visits can only be arranged by email).