Final answer:
The claim that Macbeth and Banquo defeat Macduff and Macdonwald is false. They defeat Macdonwald and the Thane of Cawdor. Macduff actually opposes Macbeth's later tyranny and is not a rebel in the early acts of the play.
Step-by-step explanation:
The statement that the rebels whom Macbeth and Banquo defeat in Act I are Macduff and Macdonwald is False. In Act I of William Shakespeare's Macbeth, the characters Macbeth and Banquo are involved in quelling a rebellion against King Duncan of Scotland. The primary rebels mentioned are the traitorous Thane of Cawdor and Macdonwald. Macdonwald is presented as a traitor who leads a revolt against the king, while Macduff is a Scottish nobleman who actually opposes Macbeth's later tyranny.
In the play, Macbeth is initially a hero, lauded for his bravery in battle, especially after defeating the rebel forces led by Macdonwald. In recognition of his valor, King Duncan bestows upon Macbeth the title of Thane of Cawdor, succeeding the former thane who was found to be a traitor. Macduff, on the other hand, emerges later in the play as a force against Macbeth's unlawful rise to power and his eventual tyranny over Scotland.