During the afternoon of 21 May, the attack by the 50th Division and the 1st Tank Brigade was progressing south from Arras. This was to be the only large scale attack mounted by the BEF during the campaign. The attack was supposed to be mounted by two infantry divisions, comprising about 15,000 men. It was ultimately executed by just two infantry battalions, the 6th and 8th Battalions Durham Light Infantry supporting the 4th and 7th Royal Tank Regiment, totalling around 2,000 men, and reinforced by 74 tanks. The infantry battalions were split into two columns for the attack. The right column initially made rapid progress, taking a number of German prisoners, but they soon ran into German infantry and SS, backed by air support, and took heavy losses.
The left column also enjoyed early success before running into opposition from the infantry units of Erwin Rommel's 7th Panzer Division. The defending forces, elements of motorized SS regiment "Totenkopf" - later to be expanded into SS-Division Totenkopf - were overrun, their standard 37 mm PaK 36/37 anti-tank guns proving ineffective against the heavily-armoured British Matilda tank. Generalmajor Erwin Rommel, commanding the 7.Panzer-Division committed some of his armour to local counterattacks, only to find the guns of the Panzer II and Panzer III tanks could not penetrate the Matildas' armour. Desperate to prevent a British breakthrough, Rommel ordered the division's 8.8cm FlaK 18 Flak and 105 mm field guns be formed into a defensive line and fire anti-tank and HE rounds in a last ditch effort to stop the Matildas. The BEF's advance was halted with heavy losses. Then, with Luftwaffe support, Rommel launched a successful counter-attack, driving the British back.Frankforce had been repulsed.