We will now relate an adventure which happened to the Flemings, under command of sir Robert d’Artois and sir Henry de Flandres. They amounted to upwards of forty thousand, from the towns of Ypres, Poperingue, Malines, Cassel, and Castlewick of Bergues. These Flemings were encamped in great array in the valley of Cassel, to oppose the French garrisons which king Philip had sent into St. Omer, St. Venant, Aire, and other towns and fortresses in that neighbourhood. By the king of France’s orders, the dauphin of Auvergne, the lords of Kaleuhen, Montay, Rochefort, the viscount de Touars, and many other knights from Auvergne and Limousin, posted themselves in St. Omer. In St. Venant, and in Aire, there were also a great many knights. The Flemings frequently skirmished with the French; and one day, to the number of four or five thousand lightly armed, they came to the suburbs of St. Omer, pulled down many houses, and pillaged wherever they could. The alarm was instantly spread in the town: the lords who were there soon armed themselves and their men, and sallied out at the gate opposite to where the Flemings were. They might amount to about six banners, two hundred armed with helmets, and six hundred infantry. They made a circuit round St. Omer, as their guides, who were well acquainted with the road, led them, and came opportunely upon the Flemings, who were busily employed in collecting every thing they could find in the town of Arques, which is close to St. Omer, so that they were dispersed about, without officers, and without order. The French attacked them thus unawares, with banners displayed, and lances in their rests, in regular order, crying out, “Clermont, Clermont, for the dauphin of Auvergne.”
When the Flemings heard this, they were sore alarmed; and, not attempting to rally in any order, they fled as fast as they could, throwing down all the pillage they had gotten. The French pursued them, and killed and knocked them down in great numbers. This pursuit lasted full two leagues: there were four thousand eight hundred slain, and four hundred captured, who were carried to St. Omer, and there imprisoned. When those few, who had escaped, arrived at their own army, and related what had happened to them, it soon came to the ears of their captains, who told them they had deserved what had befallen them, for they had done this without orders, and without a leader. About midnight, as these Flemings were asleep in their tents, so sudden an alarm and fright came upon them, that they all got up, and could not make sufficient haste to decamp. They directly pulled down their tents and pavilions, flung them into the baggage-waggons, and took to their heels; without waiting for any one, or keeping any order or regular road. When the two commanders heard of this, they got up in the greatest haste, and ordered large fires and torches to be lighted: they mounted their horses, and galloping after the Flemings, said to them, “Sirs, tell us what has ailed you, that you fly thus, when no one pursues you; you ought to think yourselves very secure, and yet you are still going on. Return back, for God’s sake: you are exceedingly to blame, to run away without being pursued.” But, notwithstanding all their entreaties, they would not stop, and each took the nearest way he could find to his own home. These lords, perceiving they could not prevail with them, ordered their baggage to be packed up in the waggons, and came to the siege of Tournay, where they related to the chiefs what had happened to the Flemings, which surprised all; some said, they must have been bewitched.