In Shakespeare's Hamlet, there is a conflict between young Fortinbras of Norway and the Danes. Hamlet's father killed Fortinbras' father in combat. Fortinbras wants revenge for his father's death, and as Horatio says, he is “Of unimproved mettle hot and full.” He also wants the lands that Hamlet's father won in his fight. Fortinbras is ready to attack at any moment.
Claudius wants to avoid war with Norway, so he is writing a letter to the king of Norway, young Fortinbras' uncle. The king is, as Claudius says, “impotent and bed-rid,” and Claudius doubts that he knows what Fortinbras is up to. But nonetheless, Claudius will ask the king of Norway to restrain his nephew. He is sending Cornelius and Voltimand with a letter to that effect.
The letter works. Indeed, the king of Norway has no idea that Fortinbras was planning to attack Denmark. He thought his nephew was going to war against Poland. The king rebukes his nephew and makes him vow never again “To give the assay of arms” against Denmark. Fortinbras swears the oath, and the king is so relieved that he gives him money and permission to really go to war against Poland if he must fight someone.