How the battle of Tewkesbury was lost and won is too well known to need description in detail here.

Whether the Lancastrian army could have held the field before the Yorkist veterans had they been skilfully generalled will never now be known; but the fiery and impetuous Duke of Somerset, whose ill-judged ardour had forced the battle upon his followers, undoubtedly lost the day for them by his intemperate and reckless disregard of the dictates of common prudence.

After opening the fight by a discharge of ordnance, he was mad enough to leave his intrenched position on the Home Ground, and carry his men into the open for a charge upon the opposing army.

Here they were not only confronted by Edward's compact army, but were taken in the flank and rear by a company of spearmen who had been told off to guard against a possible ambush in a little wood; which, however, the hot-headed Somerset had never thought to place.
Thrown into confusion, the Lancastrians were routed, and confusion was rendered worse confounded by another impetuous act on the part of the fiery young duke.

As he and his flying soldiers fell back upon the town of Tewkesbury, and reached the market place, they found Lord Wenlock and his men sitting idle and motionless there, as if there was no work for them to do.
The reason for this extraordinary apathy on the part of one of the leaders will never now be known.