The opening lines of Henry IV: Part I are given to the play's title character, as the king and founder of the Bolingbrook dynasty says, "So shaken as we are, wan with care" (I.i.1). The play begins in the midst of tumultuous historical events, the overthrow of the "sad poet" king Richard II, civil war and rebellion arising in its wake. In this first speech of the play, Henry IV expresses heartfelt relief that civil butchery is over and turns to his anointed role as a defender of Christendom and Christian England.

Forthwith a power of English shall we levy,
Whose arms were moulded in their mothers' womb,
To chase these pagans in those holy fields,
Over whose acres walk'd the blessed feet
Which fourteen hundred years ago were nail'd
For our advantage on the bitter cross.
(I.i.22-27)

Immediately we realize that England's and Henry's troubles are not over. There is a gap in the monarchy that must be filled. Henry IV cannot fill it since he is a usurper and, therefore, not a regent by blood. It is his son, Hal, born the first Bolingbrook prince, who can bring the nation together into peace and Christian harmony. But here, too, there is a problem to be resolved in the character of Hal.