The deposition of Richard II in 1399 was in some ways more of a watershed than that of Edward II in 1327, for it placed a new dynasty on the throne rather than the king's own son, as in 1327. Richard indeed had no direct heir but his nearest heir was Edmund Mortimer earl of March, great-grandson through the female line of Edward III's second son, Lionel of Clarence. However, if, as was arguable, the throne was to descend to the heir male, then Henry IV, as eldest son of John of Gaunt, duke of Lancaster, Edward's third son, had the superior claim. Whatever the exact rights of the situation, the fact that the ruling house was no longer unrivalled had implications that we need to examine.

We have seen that the belief that the Wars of the Roses were retribution on the House of Lancaster for the removal and death of Richard is no longer taken seriously, but it lingers in the view sometimes expressed that the Lancastrians were always under threat if they faltered. It is undoubtedly true that for the first part of the reign Henry IV was seriously at risk, especially from the Percies who had helped put him on the throne and demanded rewards that in the end Henry was not prepared to give. At this time, he had insufficient support among the nobility to be sure of survival and was heavily reliant on forces he could raise from his own Duchy of Lancaster.