When war was ready to break out, Northumberland was seized with a sudden illness at Berwick: and young Piercy, taking the command of the troops, marched towards Shrewsbury, in order to join his forces with those of Glendour, The king had happily a small army on foot, with which he had intended to act against the Scots; and knowing the importance of celerity in all civil wars, he instantly hurried down, that he might give battle to the rebels.

He approached Piercy near Shrewsbury, before that nobleman was joined by Glendour; and the policy of one leader, and impatience of the other, made them hasten to a general engagement.
The evening before the battle, Piercy sent a manifesto to Henry, in which he renounced his allegiance, set that prince at defiance, and, in the name of his father and uncle, as well as his own, enumerated all the grievances of which, he pretended, the nation had reason to complain; He upbraided him with the perjury of which he had been guilty, when, on landing at Ravenspur, he had sworn upon the Gospels, before the earl of Northumberland, that he had no other intension than to recover the duchy of Lancaster, and that he would ever remain a faithful subject to King Richard.

He aggravated his guilt in first dethroning, then murdering that prince, and in usurping on the title of the house of Mortimer, to whom, both by lineal succession, and by declarations of parliament, the throne, when vacant by Richard's demise, did of right belong.

He complained of his cruel policy in allowing the young earl of Marche, whom he ought to regard as his sovereign, to remain a captive in the hands of his enemies, and in even refusing to all his friends permission to treat of his ransom; He charged him again with perjury in loading the nation with heavy taxes, after having sworn that, without the utmost necessity, he would never levy any impositions upon them.

And he reproached him with the arts employed in procuring favorable elections into parliament; arts which he himself had before imputed as a crime to Richard, and which he had made one chief reason of that prince's arraignment and deposition.[*] This manifesto was well calculated to inflame the quarrel between the parties: the bravery of the two leaders promised an obstinate engagement; and the equality of the armies, being each about twelve thousand men, a number which was not unmanageable by the commanders, gave reason to expect a great effusion of blood on both sides, and a very doubtful issue to the combat.
We shall scarcely find any battle in those ages where the shock was more terrible and more constant.