The Battle of Dunkirk (French: Bataille de Dunkerque) (Also known as Operation Dynamo) was a major battle during World War II. It lasted from the 26 May until 4 June 1940. The Allied forces were split in two by a German armoured advance to the Channel coast at Calais. The British and French commanders had been taken by surprise at the speed of the advance. The northern part of the army was surrounded In Dunkirk, France, a port on the English Channel. There they made a perimeter and waited for an evacuation.