Their movement had been premature.

Surrey was still asleep, and nothing could be done until he awoke; when he did so the army armed leisurely, after which Surrey bestowed the honour of knighthood upon many young aspirants.
The number of the Scots under Wallace is not certainly known; the majority of the estimates place it below twenty thousand, and as the English historian, who best describes the battle, speaks of it as the defeat of the many by the few, it can certainly be assumed that it did not exceed this number.
Only on the ground of his utter contempt for the enemy can the conduct of the Earl of Surrey, in attempting to engage in such a position, be understood.

The bridge was wide enough for but two, or at most three, horsemen to cross abreast, and when those who had crossed were attacked assistance could reach them but slowly from the rear.
The English knights and men-at-arms, with the Royal Standard and the banner of the Earl of Surrey, crossed first.

The men-at-arms were followed by the infantry, who, as they passed, formed up on the tongue of land formed by the winding of the river.
When half the English army had passed Wallace gave the order to advance.

First Sir Andrew Moray, with two thousand men, descended the hills farther to the right, and on seeing these the English cavalry charged at once against them.