The Scots army, again made up chiefly of spear-men as at Stirling, was arranged in four great armoured 'hedgehogs' known as schiltrons. The long spears (pikes) pointed outwards at various heights gave these formations a formidable and impenetrable appearance. The gaps between the schiltrons were filled with archers and to the rear there was a small troop of men-at-arms, provided by the Comyns and other magnates.
On Tuesday 22 July, the English cavalry, divided into four battalions, (also described as battles), finally caught sight of their elusive enemy. The left was commanded by the Earls of Norfolk, Hereford and Lincoln. The right was under the command of Antony Bek, Bishop of Durham, while the King commanded the centre, still a little distance to the rear of the vanguard. Once in sight of the enemy, Norfolk and his colleagues began an immediate attack, but on encountering a small marsh to the front of the Scots position, made a long detour to the west before being able to make contact with the right of Wallace's army. Bek tried to hold back his own battalion to give the King time to get into position but he was overruled by his impatient knights, who were anxious to join their comrades on the left in an immediate attack. In a disorganised pell-mell the cavalry finally closed on the Scots, on the right and left. The party of men-at-arms under John Comyn left the field immediately.
The Scots bowmen commanded by Sir John Stewart of Bonkill, the younger brother of the High Steward of Scotland, stood their ground and were quickly destroyed. But the schiltrons held firm, with the knights making little impression on the dense forest of long spears, and a small number of riders being killed under their horses. King Edward arrived in time to witness the discomfiture of his cavalry and quickly restored discipline. The knights were ordered to withdraw and Edward prepared to employ the tactics that the Earl of Warwick had used to defeat the Welsh spearmen at the Battle of Maes Moydog in 1295. The Scottish cavalry charged the English cavalry, but seeing the vast numbers that were formed against them they then fled the field, abandoning their fellow Scottish comrades to the slaughter.
Edward's longbowmen were brought into place and quickly overcame the inexperienced force of badly armed Scottish archers. The schiltrons were an easy target; they had no defence and nowhere to hide. The hail of arrows was supplemented by crossbow and slingshot. Unable to retreat or attack, the battle was lost for the Scots almost as soon as the first arrows began to fall. The English cavalry waited, this time observing the King's command, until the Scots ranks were thin enough to allow them to penetrate the Scottish formation and cause whatever damage they could. The English footsoldiers, who had been advancing during the English barrage on the Scottish formations, closed the distance and the schiltrons finally started to break and scatter. A great many Scots were killed, including Macduff, son of the Earl of Fife. The survivors, Wallace included, escaped as best they could, mostly into the nearby forest of Torwood where their pursuers could not safely follow.