Dunkirk: The Outer and Inner Perimeters 30 May–2 June 1940

The success of the evacuation of Dunkirk – Operation Dynamo – was reliant on a strong and successful rearguard to prevent any German breakthrough that could jeopardize the operation. A 25-mile (40-km) long and 8-mile deep outer perimeter, utilizing the natural waterways and canals around Dunkirk, was the main line of defence against strong German artillery and infantry attacks. The French had responsibility for the section running from Mardyck to Bergues, and the British from Bergues to Nieuport. On the night of 1 June, the rearguard survivors from the outer perimeter withdrew to an inner perimeter, most of which bordered canals and flooded areas. The bulk of these men were then evacuated on the night of 2 June. The rearguard at Dunkirk are often seen as the true or ‘secret’ heroes of Operation Dynamo; many of them sacrificed their own evacuation to defend the crucial perimeters, and were then captured or killed.