In act one, scene two, the Captain describes Macbeth's and Banquo's heroic performances in battle as they defeated Macdonwald and the Norwegian forces. The Captain first describes how Macbeth violently killed Macdonwald during their close battle by splitting Macdonwald open from his navel to his jawbone. After Macbeth splits Macdonwald's body in two, he decapitates him and fixes his head upon the battlements. As soon as Macbeth's forces defeat Macdonwald, the Norwegian king sends his fresh troops to attack the Scottish soldiers. However, Macbeth's troops are not frightened or deterred, and they end up winning the battle. Ross finishes telling King Duncan about Macbeth's victory over the Norwegian forces and mentions that the Thane of Cawdor, who colluded with the King of Norway, has also been captured.

According to the Captain with whom King Duncan speaks in Act 1, Scene 2, Macbeth bravely confronts the traitor, Macdonwald, stabbing him in the navel and ripping him open all the way up to his jaw.  After Macbeth "unseamed" his foe, Macbeth placed Macdonwald's head on a spike on the battlements so that all can see what becomes of a traitor (1.2.24).  However, the Captain continues, Macbeth and Banquo were not done fighting yet: after the battle against Macdonwald's rebel forces was over, the rebels having fled the scene, the king of Norway saw his opportunity to attack when the loyal Scottish forces were tired and weakened.  Thus, the king ordered a new attack, with fresh soldiers, on Macbeth's army.  Although Macbeth and Banquo were clearly worried, they were victorious in this battle as well.