Henry had moved rapidly to besiege Dreux, a town controlled by the League.

As Mayenne had followed, intending to raise the siege, Henry had withdrawn but stayed within sight, deploying his army on the plain of Saint André between the towns of Nonancourt and Ivry.

The army of the Catholic League consists of citizens led by priests and rebellious nobles, Swiss infantry under Appenzell, pikemen brought from Flanders by Philip, Count of Egmont, and the troopers of the Guise family with Mayenne in command.

The battle occurs on March 14 on the plain of Épieds near Ivry (later renamed Ivry-la-Bataille), Normandy, located on the Eure River and about thirty miles west of Paris, at the boundary between the Île-de-France and the Beauce regions.

Henry's forces are victorious: Mayenne is driven back, the Duke of Aumale forced to surrender, and the Count of Egmont killed.

The Duke of Mayenne has lost the battle.

Henry, now the only credible claimant to the throne of France, pursues the losers, many of whom surrender for fear of falling into worse hands, their horses being in no condition to get them away from danger.

The countryside is full of Leaguers and Spaniards in flight, with the king's victorious army pursuing and scattering the remnants of the larger groups that disperse and re-gather; he goes on to lay siege to Paris.