In Shakespeare's Hamlet, the appearance of Hamlet's foil, Fortinbras, a man of brevity, loyalty, and bravery, provides the impetus to Hamlet's final actions. Like Hamlet, Fortinbras has had a father slain, but he immediately seeks revenge. But, unlike Hamlet the procrastinator, he is, as Claudius brazenly calls him "an opportunist." Horatio warns that Fortinbras (whose name suggests strength [fort=strong]) "is going to recover of us by strong hand" the lands that King Hamlet has taken from his father. And, like Hamlet he is the true heir to the throne of his country, the Prince of Norway as Hamlet is the Prince of Denmark. The loyalty of Fortinbras impels him to avenge his father; however, it also causes him to faithfully obey his uncle's wishes not to bear arms against Denmark while Hamlet waivers between thoughts of revenge and despairing ideas of suicide.
Finally, in Act V, when Hamlet who waivers in his loyalty to his murdered father witnesses the valor of Fortinbras, he is in awe. In his final soliloquy, Hamlet reflects,
A thought which, quartered, hath but one part wisdom
And ever three parts coward--I do not know
Why yet I live to say "This thing's to do,'
Sith I have cause, and will, and strength, and means,
To do't. Examples gross as earth exhort me:
Witness this army of such mas and charge,--
Led by a delicate and tender prince,
Whose spirit, with divine ambition puffed,
Makes mouths at the invisible event,
Exposing what is mortal and unsure
To all that fortune, death, and danger dare,
Even for an eggshell.... (4.4.46-53)
Fortinbras provides Hamlet with the inspiration to act:
....How stand I then,
That have a father killed, a mother stained, (4.4.56-57)
Unconsciously fulfilling the desire of the Prince of Norway, the Prince of Denmark in his valor rids Denmark of its corrupt court. As all of the court of Denmark are slain, fortuitously, Fortinbras enters. And, ironically, the looming threat of this Prince of Norway's revenge is fulfilled, not as a threat, but as a reward to him who has "some rights of memory in this kingdom" (5.2.369). It is also ironic that Fortinbras's inaction of not attacking Denmark provides him reward, while Hamlet has suffered because of his inaction. Nevertheless, in this reward to Fortinbras, that "delicate and tender prince," Hamlet acts with valor and achieves victory over the corrupt court of Denmark, receiving a soldier's burial by decree of Fortinbras., who declares,
The soldier's music and the rite of war
Speak loudly for him. (5.2.178-179)
Fortinbras' appearance in Act 5 is at best ambiguous. He is, of course, Hamlet's foil. He was ready to act quickly to recover the lands his father lost to Denmark. But Claudius negotiates a deal with Fortinbras' uncle, and Fortinbras' agrees to invade Poland instead. Fortinbras' direct actions to avenge his father's death and recover the lands fail. He is thwarted by his elders.
Hamlet does not proceed as directly as Fortinbras does in his vengeance. He is craftier and more cunning, and therefore stands a better chance at success. His mad act is quite clever and gives him an opportunity to disguise his true motives. But Hamlet has more scruples than Fortinbras and is unwilling to act against someone who may be innocent. Thus, Hamlet delays. It can be argued, however, that Hamlet's delay helps keep him alive. Rash actions have severe consequences in this rotten world of Denmark.
Fortinbras wins almost by default. He comes through Denmark because he has been granted safe passage-way. He has not come to attack. But to his surprise, he finds the implosion of the royal family. I think it important that Shakespeare has the family destroyed from within, not from without. It is also important to note that Fortinbras did not directly cause Denmark to fall to him. Almost by his inaction toward Denmark, Fortinbras wins.
Hamlet in his dying breath gives his right to the throne to Fortinbras. We don't know if Fortinbras will be a good leader. He has done nothing really to prove himself. Sending men to their graves over a worthless piece of land in Poland seems hardly admirable. Yet, he is young, brave, and loyal to his family. Perhaps he can restore order.
He gives Hamlet a soldier's funeral. The fact that at the end, he recognizes Hamlet's noble nature gives us most probably Shakespeare's own pronouncement of his character. Through Fortinbras' eyes we see what a noble prince has been destroyed and we are filled with the notion that a tremendous talent has been wasted. Fortinbras is at best a poor substitute, but we are hopeful that he will rule Denmark with honor.
Fortinbras is perhaps the strangest. He is barely seen and speaks little. Other characters often speak of him in low tones. Oddly enough, though, Fortinbras is a stabilizing force in the action of the play and he also functions as a framing device for the play itself. He makes his presence known only at the beginning, middle and end. click the link to read more