The Percys' preparations could not be carried on without exciting attention; and in March the king, seeing that the open defiance of his authority, by the release of the Scottish prisoners, would assuredly be followed by armed rebellion, which the Douglas would probably have pledged himself to aid as the condition of his release, began, on his side, to make similar preparations.

Levies were called out, and the Prince of Wales was appointed to the command of the Welsh marches, and the governorship of Wales.
Towards the end of June Douglas, faithful to his agreement, crossed the frontier; and was at once joined by Hotspur, with the force he had gathered.

Hotspur's father was lying sick at Berwick, but was to follow, as speedily as possible, with the army collected in the north of the county, and from Dunbar's estates.
It had been arranged that Glendower should meet the allies at Lichfield; and on his being joined by his uncle, the Earl of Westmoreland, with his following, Hotspur marched south.

His intention was, after effecting a junction with Glendower, to march and give battle to the army with which Henry and the Prince of Wales were advancing against him.

At Lichfield, however, he learned that Glendower had not completed his preparations in sufficient time to join him.