Somerset was quick to take advantage of his success, and wheeling his men round fell upon the Duke of Gloucester's division, and was equally successful in his attack upon it.

Had the centre, under Lord Wenlock, moved forward at once to his support, the victory would have been assured; but Wenlock lay inactive, and Somerset was now engaged in conflict with the whole of Edward's force.

But even under these circumstances he still gained ground, when suddenly the whole aspect of the battle was changed.
Before it began Edward had sent two hundred spearmen to watch a wood near the defenders' lines, as he thought that the Lancastrians might place a force there to take him in flank as he attacked their front.

He ordered them, if they found the wood unoccupied, to join in the fight as opportunity might offer.

The wood was unoccupied, and the spearmen, seeing the two divisions of their army driven backwards, and being thereby cut off from their friends, issued from the wood and, charging down in a body, fell suddenly upon Somerset's rear.
Astounded and confused by an attack from such a quarter, and believing that it was an act of treachery by one of their own commanders, Somerset's men, who had hitherto been fighting with the greatest bravery, fell into confusion.