This force comprised five hundred Belgian heavy dragoons under the chief nobles of the land, together with a selection, in even proportions, of Walloon, German, Spanish, and Italian troopers.
Mayenne accordingly crossed the Seine at Mantes with an army of ten thousand foot, and, including Egmont's contingent, about four thousand horse.

A force under Marshal d'Aumont, which lay in Ivry at the passage of the Eure, fell back on his approach and joined the remainder of the king's army.

The siege of Dreux was abandoned; and Henry withdrew to the neighbourhood of Nonancourt.

It was obvious that the duke meant to offer battle, and it was rare that the king under any circumstances could be induced to decline a combat.
On the night of the 12th-13th March, Henry occupied Saint Andre, a village situated on an elevated and extensive plain four leagues from Nonancourt, in the direction of Ivry, fringed on three sides by villages and by a wood, and commanding a view of all the approaches from the country between the Seine and Eure.

It would have been better had Mayenne been beforehand with him, as the sequel proved; but the duke was not famed for the rapidity of his movements.