Edward placed himself in the centre of his array, the Duke of Gloucester commanded on his right, and Lord Hastings on his left.

Desirous, from his inferiority in artillery, to fight out the battle hand to hand, Edward, at six o'clock in the morning, ordered his trumpets to blow, and, after firing a few shots, advanced through the mist to attack the enemy. His misconception as to Warwick's position, which had saved his troops from the effects of the cannonade during the night, was now disadvantageous to him, for the Earl's right so greatly outflanked his left that when they came into contact Hastings found himself nearly surrounded by a vastly superior force. His wing fought valiantly, but was at length broken by Oxford's superior numbers, and driven out of the field. The mist prevented the rest of the armies from knowing what had happened on the king's left. Edward himself led the charge on Warwick's centre, and having his best troops under his command, pressed forward with such force and vehemence that he pierced Somerset's lines and threw them into confusion.

Just as Warwick's right had outflanked the king's left, so his own left was outflanked by Gloucester. Warwick's troops fought with great bravery, and, in spite of the disaster to his centre, were holding their ground until Oxford, returning from his pursuit of the king's left, came back through the mist. The king's emblem was a sun, that of Oxford a star with streaming rays. In the dim light this was mistaken by Warwick's men for the king's device, and believing that Oxford was far away on the right, they received him with a discharge of arrows. This was at once returned, and a conflict took place. At last the mistake was discovered, but the confusion caused was irreparable. Warwick and Oxford each suspected the other of treachery, and the king's right still pressing on, the confusion increased, and the battle, which had been so nearly won by the Earl, soon became a complete defeat, and by ten in the morning Warwick's army was in full flight.

Accounts differ as to the strength of the forces engaged, but it is probable that there was no great inequality, and that each party brought some fifteen thousand men into the field. The number of slain is also very uncertain, some historians placing the total at ten thousand, others as low as one thousand; but from the number of nobles who fell, the former computation is probably nearest to the truth. Warwick, his brother Montague, and many other nobles and gentlemen, were killed, the only great nobles on his side who escaped being the Earls of Somerset and Oxford; many were also killed on Edward's side, and the slaughter among the ordinary fighting men was greater than usual.

Hitherto in the battles that had been fought during the civil war; while the leaders taken on the field were frequently executed, the common soldiers were permitted to return to their homes, as they had only been acting under the orders of their feudal superiors, and were not considered responsible for their acts. At Barnet, however, Edward, smarting from the humiliation he had suffered by his enforced flight from England, owing to the whole country declaring for his rival, gave orders that no quarter was to be granted. It was an anxious day at St. Albans, where many ladies whose husbands were with Warwick's army had, like Dame Tresham, taken up their quarters. It was but a few miles from the field of battle. In the event of victory they could at once join their husbands, while in case of defeat they could take refuge in the sanctuary of the abbey. Messengers the night before had brought the news that the battle would begin at the dawn of day, and with intense anxiety they waited for the news.

Dame Tresham and her son attended early mass at the abbey, and had returned to their lodgings, when Sir Thomas rode up at full speed. His armour was dinted and his plume shorn away from his helmet. As he entered the house he was met by his wife, who had run downstairs as she heard his horse stop at the door. A glance at his face was sufficient to tell the news.

“We have lost the day,” he said. “Warwick and Montague are both killed. All is lost here for the present. Which will you do, my love, ride with me to the West, where Queen Margaret will speedily land, if indeed she has not landed already, or take sanctuary here with the boy?”

“I will go with you,” she said. “I would vastly rather do so.”

“I will tell you more on the road,” he said. “There is no time to be lost now.”

The woman of the house was called, and at once set her son to saddle the other horse and to give a feed to that of the knight. Dame Tresham busied herself with packing the saddlebags while her husband partook of a hasty meal; and ten minutes after his arrival they set off, Gervaise riding behind his father, while the latter led the horse on which his wife was mounted. A thick mist hung over the country.