Simon the Coldheart by Georgette Heyer

At the time of Simon's seventeenth birthday, affairs in Wales and the North of England had reached something approaching a crisis. It was in the year 1403, when Bolingbroke had sat upon the throne for four years, and his son, Henry of Monmouth, had held the reins of government in Wales, unassisted, for some months only. Although he was but sixteen years of age, the Prince had already led a punitive expedition into North Wales, and considerably harried the rebel, Owen Glyndourdy. But now Percy, the redoubtable Hotspur, had, with his father, the Earl of Northumberland, and his uncle, the Earl of Worcester, raised his standard in the North against the King, and was on the point of marching to join Glyndourdy in Wales.

It was in July that these state affairs first affected Montlice, although for some time past Fulk, ever-ready for war, had chafed and fretted in his fair land, debating whether he should take his men to join the Prince on the Marches or no. His uncertainty rendered him irritable to all who crossed his path; only Simon understood the reason of this irritability, and he gave no sign that he understood. But although he said little, he too was watching affairs, and under his habitual placidity was a glowing desire to be gone from quiet Montlice to Shrewsbury where lay the Prince of Wales with his insufficient army and his insufficient supplies.