In Act 1, scene 2, we learn that Macbeth fought his way through the soldiers until he reached the rebel Macdonwald, then literally cut him in half with his sword - "unseam'd him from the nave to the chops" - and stuck his head on the battlements (a typical ending for a traitor.) We also learn that Cawdor, Duncan's supposed good friend, has betrayed him and joined the Norwegian enemy, but is now defeated.
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