The French, under Charles VII, had taken the time offered by the Treaty of Tours in 1444 to reorganize and reinvigorate their armies. The English, without clear leadership from the weak Henry VI, were scattered and dangerously weak. When the French broke the truce in June 1449 they were in a much improved position.

The English had gathered a small army during the winter of 1449. Numbering around 3,400 men, it was dispatched from Portsmouth to Cherbourg under the command of Sir Thomas Kyriell. Upon landing on 15 March 1450, Kyriell's army was reinforced by with forces drawn from Norman garrisons.

At. Formigny, the French opened the engagement with a failed assault on the English position with their dismounted men-at-arms. French cavalry charges on the English flanks were also defeated. Clermont then deployed two culverins to open fire on the English defenders. Unable to withstand the fire, the English attacked and captured the guns. The French army was now in disarray.

At this moment the Breton cavalry force under Richemont arrived from the south, having crossed the Aure and approached the English force from the flank. As his men were carrying off the French guns, Kyriell shifted forces to the left to face the new threat. Clermont responded by attacking again. Having abandoned their prepared position, the English force was charged upon by Richemont's Breton cavalry and massacred. Kyriell was captured and his army destroyed. A small force under Sir Matthew Gough was able to escape.

Kyriell's army had ceased to exist. With no other significant English forces in Normandy, the whole region quickly fell to the victorious French. Caen was captured on 12 June and Cherbourg, the last English-held fortress in Normandy, fell on 12 August.