All means of communication in and out of Dunkirk – road, rail and canal – passed through Furnes on the outer perimeter. Should the Germans capture it, they could roll up the embarkation beaches. Third Division defended the perimeter from the east. By the time the division arrived at Furnes nearly 100,000 troops, British and French, had already escaped. But the Allies would need four more days to embark all of their men.

Thanks to the waterlogged ground, the defenders could only dig in along the edges of the roads and banks. At 1715, after heavy artillery preparation, two battalions from the 192nd Infantry Regiment tried to cross the canal using assault boats, just north of Furnes, at the junction between the Royal Engineers and the Berkshires. Although many German boats sank in mid-canal, by dusk they had gained a temporary footing on the near bank. To prevent a complete encirclement of the town, carriers from 2nd Grenadiers and a company of the 1st Coldstream Guards took over part of the position. These reinforcements rallied the dispirited troops, went in with the bayonet and restored the line. At about 2200 the Germans attacked again and temporarily broke across the canal but the British front remained intact up to the moment of withdrawal.