Malcolm, Duncan's eldest son, has fled to England. He is joined there by Macduff. Together they persuade the English king to give them an army of 10,000 men. They invade Scotland. Macbeth is easy to defeat because he has alienated so many of the thanes through his tyrannous rule that he is virtually defenseless. Macbeth himself meets Macduff on the field of battle and is killed in a death duel. Too late, Macbeth realizes that he has been deceived by the prophecies of the three witches, who told him that he could not be defeated until Birnam Wood moved to Dunsinane and that no man of woman born could ever overcome him. Macduff informs Macbeth:
Despair thy charm,
And let the angel whom thou still hast served
Tell thee Macduff was from his mother's womb
Malcolm will become the new king of Scotland. Please refer to the summary and analysis of the final act of the play by clicking on the eNotes reference link below.