By the 21 May, German tanks were approaching Boulogne-sur-Mer. John Colville in his diary entry that day said preparations for the evacuation of the British Expeditionary Force (BEF) were being made in case of necessity. An estimated 400,000 Allied servicemen, mostly of the BEF with elements of the French First Army, had retreated into the coastal area. Their hopes rested mostly on the success of the Weygand Plan, a proposed counter-offensive by themselves in conjunction with a strike from the south by the main French forces. This did not come to fruition and the BEF commander, Lord Gort, decided that evacuation was the only option. During 23 and 24 May, the Royal Navy evacuated an estimated 4,365 servicemen from Boulogne.