What was the codename used for the 1940 Dunkirk evacuation?

Operation Dynamo, the evacuation from Dunkirk of 27 May-4 June 1940, is one of the most celebrated military events in British history, and yet it was the direct result of one of the most crushing defeats suffered by the British army. Only eighteen days before the start of the evacuation the combined British and French armies had been seen as at least equal to the Germans. If Belgium and Holland came into the war, then the combined Allied armies could field 144 divisions, three more than the Germans. Even without Belgium and Holland the Allies outnumbered the Germans by almost two-to-one in artillery and by nearly 50% in tanks. For over six months the two armies had faced each other across the Franco-German border, but on 10 May the German offensive in the west began, and that all changed. After only ten days German tanks reached the Channel at Abbeville, splitting the Allied armies in two. All the Germans had to do to trap the BEF without any hope of escape was turn north and sweep along the almost undefended channel coast.