Why does ducan order cawdors execution?

Duncan orders Cawdor's execution because he has discovered that the Thane of Cawdor has betrayed him by siding with the rebels against the Scottish crown. Duncan seeks to demonstrate his authority and the consequences of treachery by executing Cawdor, thereby reinforcing loyalty among his other subjects. This act also serves as a pivotal moment that foreshadows the themes of betrayal and ambition in the play "Macbeth."