The Battle of Formigny (April 15, 1450) was a clash of the Hundred Years' War. It meant a decisive victory for the French.

The French, under Charles VII, had taken the time offered by the Truce of Tours 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. Pont-Audemer, Pont-L'Evêque and Lisieux fell in August and much of Normandy was retaken by October. Cutting north and east the Bureau brothers oversaw the capture of Rouen (October 1449), Harfleur (December 1449), Honfleur and Fresnoy (January 1450), before moving on to invest Caen.

The English had gathered a small army during the winter of 1449. Numbering around 3,000 men, it was dispatched from Portsmouth to Cherbourg under the command of Sir Thomas Kyriell . Landing on March 15, 1450, the army was reinforced with a further 2,000 men under Sir Matthew Gough in late March. Kyreill advanced south and captured Valognes in a bloody clash, as further south two French armies joined (around 5,000 men under Comte de Clermont ) and marched north for Caretan .

The English army circled Caretan on April 12, the French declined to sally although there were a number of smaller skirmishes. Kyriell turned east towards Bayeux, reaching the village of Formingy on April 14. At the same time a third French force, under the Condéstable de Richmont, had reached St. Lô from the south.

On April 15 Clermont's forces were sighted by the English. The armies faced each other on the Carenten-Bayeux road, near a small tributary of the Aure, the English with their back to the stream. The English formation numbered around 4,000 — with a three-to-one preponderance in archers — and gathered in a long line behind a thicket of stakes and low earthworks.

Clermont opened the engagement with attacks against the flanks and small charges; these had little chance of success and were easily turned away. He then advanced two cannon. After a period of fire that caused noticeable casualties the English charged and captured the guns.

These initial skirmishes took some three hours. At this time the French army under Richemont arrived from the south, having crossed the Aure and now approaching the English force from behind. They numbered almost 1,200 men - almost all mounted judging from the pace of their march.

Kyriell drew back from Clermont and shifted his force into an "L", straddling the steam. With the prepared position abandoned and split by the enemy's firepower the English force was soon overwhelmed in a series of charges. Kyriell was captured and his army shattered.

The English had been dealt a major blow, 2,500 killed or seriously wounded and 900 taken prisoner while French casualties were no more than 300. With no other significant English forces in Normandy the whole region quickly fell to the victorious French. The advance continued elsewhere, quickly sweeping up all English possessions except Calais.

The battle is often cited for the first decisive use of cannon. This is rather difficult to judge, contemporary accounts are dubious and it can be seen that the arrival of a second French force to the rear of the English was more significant.