Later on down the line, Macduff flees to England and meets up with Ducan son Malcolm who is air to the throne to talk to him about how Macbeth is being a tyrant and how they need to stop them. Malcolm doesn't believe Macduff is really there to help but after Ross came back and told Macduff that Macbeth had his family killed Malcolm saw how angry Macduff was and how he wanted revenge.
Macbeth visits the witches and when he does apparitions appear to him and the first one was an armored head telling him to beware Macduff and the second one was a bloody child said no man of woman born will harm Macbeth and the last one was a child w/crown and tree and he said don't worry Macbeth you won't be defeated until Birman wood marches to Dunsinane Hill.
The prophecies became true, Birnam wood begins to march towards Dunsiname. The Scotland army were not trying to fight the England army because it was a fight against Macduff and Macbeth. Macbeth meets face to face with Macduff to fight.
Macbeth and Macduff fight and at the time Macbeth thinks he can be harmed by anybody but MacDuff reveals during the fight that he was not woman born so Macbeth became scared and started thinking that he wouldn't win the fight and he was right Macduff ended up cutting his head off and Malcolm took his rightful place as king.