The Siege of Lille and Other Rearguard Action
Most troops. But not all. Some units were held back to delay the advancing German ground forces. On May 28, at the town of Lille, 40 miles south of Dunkirk, 40,000 men from the French First Army stood against seven divisions of the German forces.
They successfully held out until May 31 when, out of food and ammunition, they were compelled to surrender. But their efforts had allowed 75,000 French troops to join those gathering with the British at Dunkirk.
British troops also played their part. In early June, just as the evacuation was reaching its close, the 51st division of the BEF, under the command of the French Tenth Army helped hold the line of allied defense along the River Somme. When the line finally broke, the Germans took some 10,000 members of the 51st division along with French troops as prisoners. They transported the captured allies to prisoner-of-war camps in Poland where most remained there until the end of the war.
But their sacrifice was not in vain. The efforts of these brave defenders delayed the German advance by four days. During that time, a further 100,000 troops were able to escape to the safety of the coast. By May 29, most of the BEF forces and the remains of the French army had reached Dunkirk. It is doubtful this could have happened without the rearguard protection.