Who is the traitor that Duncan executed in Macbeth? Who was Thane of Glamis and Thane of Cawdor before Macbeth?
When the play begins, Macbeth is already the thane of Glamis. He is described as "brave" in battle and as "valor's minion." The captain with whom Duncan speaks tells him that Macbeth,
Disdaining fortune . . . carved out his passage
Till he faced the slave;
Which ne'er shook hands, nor bade farewell to him,
Till he unseamed him from the nave to th' chops,
And fixed his head upon our battlements (1.2.17-22)
In other words, exhausted though Macbeth was, he managed to fight his way to the rebel, Macdonwald, plunging his sword into the traitor's belly and ripping upward until he sliced the man open from the guts to the chin. Then, he beheaded Macdonwald and stuck his head upon the castle walls as a warning to others.
As soon as Macbeth finished with Macdonwald, he turned around to see that the Norwegian king is ready to attack his forces. The king of Norway was "assisted by that most disloyal traitor, / The thane of Cawdor" (1.2.52-53). As a result of his treason, Duncan has the thane of Cawdor executed, and he awards that title to Macbeth for his bravery and loyalty. Duncan says,
No more that thane of Cawdor shall deceive
Our bosom interest: go pronounce his present death,
And with his former title greet Macbeth (1.2.64-66)
Duncan says that the old thane of Cawdor will not deceive him any more, and he orders the thane of Ross to execute him and give the title to Macbeth.
In Shakespeare's Macbeth, three rebels lead the revolt against King Duncan.
- Macdonwald is a powerful opponent and for a while he appears to be winning his portion of the battle, but Macbeth saves the day for Duncan's forces when he "...unseamed him from the nave to th' chops,/And fixed his head upon our battlements" (1:2), according to the "bloody man" who reports about the battle to Duncan.
- The King of Norway joins the battle when he sees an opportunity, but is defeated and forced to pay "Ten thousand dollars" to attain peace and be allowed to bury his slain men.
- The Thane of Cawdor assists the king of Norway, and is defeated when Norway is. He is executed on Duncan's order and his title, Cawdor, is given to Macbeth.
These are the three rebels of Act I.
Macbeth is the Thane of Glamis at the start of the play. We have no idea who held this title before he did.
The Thane of Cawdor was leading another group of troops against King Duncan. When Duncan is told of this, he has the Thane of Cawdor executed. There were three leaders who were fighting against Duncan. Cawdor was one of them, Macdonald was another.
So the traitor that the king executes is the previous Thane of Cawdor. After he is executed, his title is given to Macbeth as a reward for how well he did in battle.