There is a certain justice to this, as at the start of the play, the audience is made aware of the political history between Norway and Denmark. Old King Hamlet killed Fortinbras's father, leading Fortinbras to want to avenge his father's death and reclaim the lands Norway lost when his father died. In many ways, Fortinbras serves as a foil for Hamlet; both are princes who have lost their fathers and desire revenge. Unlike Hamlet, however, Fortinbras is brash and decisive, willing to act quickly to take what he wants. Hamlet admires this about him, which is perhaps why he requests that Fortinbras be crowned the new king.

When Fortinbras arrives at the end of the final scene, it is after his defeat of Poland and with a canon volley, as Osric reports:

Young Fortinbras, with conquest come from Poland,
To th’ ambassadors of England gives
This warlike volley (5.2.387–389).

As he beholds the corpses strewn about the room, Fortinbras is shocked, but he also acknowledges his rightful position to claim the throne:

For me, with sorrow I embrace my fortune.
I have some rights of memory in this kingdom,
Which now to claim my vantage doth invite me (5.2.431–433).

Fortinbras is sympathetic and respectful towards Hamlet, giving instructions that Hamlet's body be carried off with honor, like a soldier. This, in addition to the fact that Fortinbras has a rightful claim to the throne of Denmark, makes it a fitting resolution for the audience to see Fortinbras as king at the end of play.