The siege of Calais (1940) was a battle for the port of Calais during the Battle of France. The siege was fought at the same time as the Battle of Boulogne, just before Operation Dynamo, the evacuation of the British Expeditionary Force (BEF) through Dunkirk. After the Franco-British counter-attack at the Battle of Arras, German units were held back to be ready to resist a resumption of the counter-attack on 22 May, despite the protests of General Heinz Guderian, the commander of the XIX Armee Korps, who wanted to rush north up the Channel coast to capture Boulogne, Calais and Dunkirk. An attack by part of the XIX Armee Korps was not authorised until 12:40 a.m. on the night of 21/22 May.