The counts of Flanders, Boulogne, Blois, and Eu, partly moved by the general jealousy arising from Henry's power and ambition, partly allured by the prospect of reaping advantage from the inconsiderate temper and the necessities of the young prince, declared openly in favor of the latter.

William, king of Scotland, had also entered into this great confederacy; and a plan was concerted for a general invasion on different parts of the king's extensive and factious dominions.
Hostilities were first commenced by the counts of Flanders and Boulogne on the frontiers of Normandy.

Those princes laid siege to Aumale, which was delivered into their hands by the treachery of the count of that name: this nobleman surrendered himself prisoner; and on pretence of thereby paying his ransom, opened the gates of all his other fortresses.
The two counts next besieged and made themselves masters of Drincourt; but the count of Boulogne was here mortally wounded in the assault; and this incident put some stop to the progress of the Flemish arms.
In another quarter, the king of France, being strongly assisted by his vassals, assembled a great army of seven thousand knights and their followers on horseback, and a proportionable number of infantry; carrying young Henry along with him he laid siege to Verneuil, which was vigorously defended by Hugh de Lacy and Hugh de Beauchamp, the governors.

After he had lain a month before the place, the garrison, being straitened for provisions, were obliged to capitulate; and they engaged, if not relieved within three days, to surrender the town, and to retire into the citadel.

On the last of these days, Henry appeared with his army upon the heights above Verneuil.