The success of Overlord was in part dependent on detailed topographical map information about the beaches and coastal towns along the French coast.British experience of Galipolli in the First World War, with the loss of 100,000 dead or wounded troops, meant that detail was necessary to ensure the invading army did not get stuck on the beach.On New Year's Eve 1943/4, under the leadership of Major Logan Scott-Bowden of the Royal Engineers, a unit set out in motor torpedo boats to survey Luc-sur-Mer.Transferring to a hydrographical survey craft, they moved closer to shore where Major Logan Scott-Bowden and Sgt Bruce Ogden-Smith swam to the beaches.On the third night, they were due to go ashore off the Orne Estuary (Sword), but by this stage fatigue (the crew and divers had been living on little more than benzedrine tablets) and the worsening weather caused Hudspeth to shorten the operation, returning to HMS Dolphin on 21 January 1944.