Overview: The Second World War Normandy landings helped seal Winston Churchill's reputation as a great wartime leader, but 29 years earlier his first D-Day - the disastrous assault on Gallipoli in 1915 - almost finished his military career. Underwater footage of sunken battleships in the Dardanelles and revealing evidence left on the Turkish beaches are reminders of the bitter lessons learnt prior to the successful invasion of Normandy in 1944.