For a time the garrison at the castle had but little to do.

Lord Grey had taken no steps to recover the estates from which his retainers had been so unceremoniously ejected.

He had, indeed, marched a strong force through them; but the Welsh had entirely withdrawn, and it would be necessary to keep so large a force unemployed, were he to reoccupy the land, that he abstained from taking any decisive action, prior to the return of the messenger whom he had despatched to inform the king of the forcible measures that Glendower had taken to recover the estate.
It would have been no trifling step to take, to carry his arms into Wales, and so bring on a fresh struggle after so many years of peace; and he would not move in the matter, until he had the royal authority.
Henry lost no time in replying.

Glendower had been an open supporter of Richard, and had retired from court rather than own his successor as king.

He had made his complaints against Lord Grey before Parliament, and his appeal had been rejected by an overwhelming majority.