what dramatice purpose is served by the arrival of Fortinbras as the play ends?

With the arrival of Fortinbras, the tone shifts dramatically in the other direction. Fortinbras, whose own barely-limned plot is extremely similar to Hamlet's (his identically-named father dead, his rise in Norway impeded by his uncle, etc.), in nonetheless Hamlet's opposite. He is a man of action, a man like Laertes, or Old Hamlet. As Hamlet predicts, he hardly wastes a moment in declaring his intention to take the throne of Denmark for his own. And, as a final irony, Fortinbras misunderstands the dead prince, and gives him a soldier’s funeral. Though we know very little of him, it seems that Fortinbras is the anti-Hamlet – a man who can only understand others in light of his own simple and straight-forward mind. Hamlet, because he was a prince, was probably a soldier, so he is given a soldier’s burial. In an exact opposite way, Hamlet finds a universe of variety within his own mind; he explores the world from many perspectives, searches many questions, revolves all but resolves nothing. Fortinbras’ arrival marks the end of the true reign of Hamlet, not Claudius’ petty and incompetent rule, but Hamlet’s regime of the mind and the possibilities of subjectivity.