When we first meet Macbeth it is in battle. He has just fought in battle and killed Macdonwald, a traitor to the king by cutting him in half through the center of his body and cut of his head to bring back as a trophy. This scene shows how brutal and unprofessional Macbeth really is. His way of judgement his death by his sword instead of taking prisoners and having them going on trial to be hung which is the "king" way to do things. This shows that Macbeth could never be a great king because violence is his first resort to problems. This like that one friend who is really buff and strong and his first reaction to something is 'fight me", but not very smart so you know he cant make the big decisions.