How is one of the witches prophecies coming true?

One of the witches' prophecies that is coming true is the rise of Macbeth. In the first scene of the play, the witches predict that Macbeth will become Thane of Cawdor and eventually King of Scotland. This prophecy begins to come true when Macbeth is named Thane of Cawdor by King Duncan after the previous Thane is executed for treason. This fulfillment of the witches' prophecy sets in motion a chain of events that leads to Macbeth's eventual downfall.