A Bloody Field by Shrewsbury

From Edith Pargeter, who also wrote as Ellis Peters, A BLOODY FIELD BY SHREWSBURY is a vivid medieval tale of Henry IV's kingdom in crisis. 'Chivalry, treachery, conflict of loyalties... The clash of wills is as stirring as the clash of steel' Observer England, 1399. A treacherous plot has been hatched to depose King Richard and install Henry Bolingbroke on the English throne. With the aid of his powerful friend Hotspur, Henry is victorious.
But, crowned Henry IV, he rules a kingdom in crisis. In Wales, rebellion threatens. Henry's heir, Hal, is named Prince of Wales but the Welsh have a prince of their own blood and he is calling them to arms. More dangerous still, a rift is opening between Henry, Hotspur and Hal. As tension mounts, the three men are inexorably drawn into a bloody collision on which the fate of the realm will hang...