organise themselves, ensuring that the seaborne troops could not be attacked during the vital first few hours after landing when they were most vulnerable. Background Operation Tonga originated in the planning of Operation Overlord, the Allied plan for the eventual invasion and liberation of German-occupied France. Invasion planning begun in May 1943, when President Franklin D. Roosevelt and British Prime Minister Winston Churchill met during the Washington Conference. The two Allied leaders decided that all available Allied forces should be concentrated in the United Kingdom, and that planning for the invasion of North-Western Europe should begin. A provisional target date of May 1944 was set with the code-name 'Overlord' decided upon. A joint Anglo-American planning staff was created under lieutenant-general Frederick E. Morgan, who was given the title of Chief of Staff to the Supreme Allied Commander (COSSAC). Early drafts of Overlord called for the commitment of airborne forces to support the ground forces and protect their landing areas. Operation Skyscraper, for example, called for the deployment of two airborne divisions to support the beach landings that would be made by five infantry divisions. One airborne division would land near Caen, and another on the east coast of the Cotentin Peninsula. "Plan C", an ambitious proposal put forward by General George C. Marshall, the Chief of Staff of the United States Army, would have involved a large airborne drop on the River Seine, aiming to cut the German forces in half during D-Day itself. Morgan and his staff finally decided that the invasion should take place along a thirty-mile front from the River Orne westwards. The final plan would utilise three divisions in the first assault, with airborne forces being dropped onto the town of Caen early on the first day to seize the first breakout route. Following the appointment of General Sir Bernard Montgomery to the command of the 21st Army Group and overall command of all ground forces to land in Normandy, the plan underwent a number of further revisions. On 21 January 1944, a revised Overlord plan was presented to General Dwight D. Eisenhower, who had been chosen as the Supreme Allied Commander for the invasion. Montgomery's revised plan widened the landing area to include all of the coastline between the River Orne and the eastern coast of the Cotentin Peninsula; five divisions would land on the beaches, and supported by three airborne divisions to land on