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In Act 1 a wounded captain has come out of the battle to tell King Duncan about the manner in which Macbeth has destroyed the merciless Macdonwald. The passage is perhaps the most violent in all of Shakespeare.
Till he unseamed him from the nave to th’ chaps
And fixed his head upon our battlements. (!.ii.20-21)
Later, one of the nobles is explaining to King Duncan about another tremendous victory of Macbeth and Banquo’s in which Macbeth is described as Bellona’s bridegroom. Because Bellona is the goddess of war, this means that Macbeth is being called the god Mars himself, a great killing machine. It is this extraordinary personage, a man of ordinary intellect but a fantastic power of imagination that has a tremendous potential and skill for killing. Shakespeare sets Macbeth up as a killer from the very beginning of the play.