The German army breached French defenses at Sedan and turned to the English Channel. On May 20th, they reached the coast and threatened to cut off both the British Expeditionary Force in Belgium and the French troops fighting there. After reaching the coast, the Germans turned north. The Allied forces were now battling in an area with Dunkirk in the center. The Germans believed that the area around Dunkirk was not suitable for tank forces and feared an Allied breakout. Therefore, the army requested and Hitler approved a halt to allow forces to regroup. The German army halted for three days, a critical period that allowed the Allies to organize a defensive perimeter around Dunkirk. By the time the Germans resumed their attack three days after halting it on May 23rd, the Allies had strong lines in place and were able to temporarily hold back the German advance.

While the Germans were being held back at the perimeter, the British had dispatched every available sea-worthy vessel to Dunkirk to embark their troops. From May 27th to one 4th, despite repeated air attacks and artillery fire, 338,228 men escaped, including 139,997 French, Belgian, and Polish troops. A total of 861 ships were used, of which 243 were sunk.