In Macbeth Act I, Macbeth is revered for his courage, valor, and bloodthirstiness in battle. Macbeth engages Macdonwald, a traitor, and guts him from neck to navel. Then, he and Banquo fight the Norwegians and Irish back after they mount a counter-attack. Together, the two thanes changed the tide of battle to bring Scotland victory. As a reward, Macbeth is given the title Thane of Cawdor. As such, he is the highest ranking thane in the land, fourth only to the King and his two sons.
From then on, Macbeth turns to villainy. He murders the King and his guards, his best friend, and Macduff's family. He commits the worst crimes imaginable: regicide and parricide, and he makes a pact with witches in doing so. He basically sells his soul to the devil for a taste of power. He and his wife go mad, though Macbeth is valiant until the end. He puts up a fight instead of committing suicide. He dies as he is first described: bathed in blood.
In act 1 sc.2 of Shakespeare's play, the bleeding sergeant reports to King Duncan how great Macbeth proved himself to be in the field of battle. As Duncan's forces were challenged by the rebel, Macdonwald, the prognosis was not good--'Doubtful it stood;/ As two spent swimmers, that do cling together/ And choke their art'. Then Macbeth appeared on the scene. Fortune who so long favored the rebel, was immediately disdained by Macbeth who 'with his brandish'd steel / Which smok'd with bloody execution, / Like Valour's minion carv'd out his passage / Till he fac'd the slave...'. Noble and heroic Macbeth gave the rebel no chance to combat, for he instantly 'unseam'd him from the nave to the chaps, / And fix'd his head upon our battlements'.
Later, when the Norwegian forces started fresh offensive with re-inforcements, Macbeth, along with the other general, Banquo, fought bravely and incoparably to hold the flags of Duncan's kingship high. The noble and brave Macbeth is called 'Valour's minion' and 'Bellona's bridegroom', phrases which refer to his heroism in superlative terms.
But the same noble and heroic Macbeth kills Duncan in his sleep. The king who visits Macbeth's castle in respectful recognition of Macbeth's contribution, is conspiratorially put to death by his most loved host and hostess. Macbeth thereafter gets Banquo killed by murderers appointed to eliminate both Banquo and his son, Fleance. Then, the whole family of Macduff is massacred--his wife, children and everybody else. Assuming the throne by a secret murder, Macbeth thus went down from murder to murder , unleashing a reign of terror in Scotland.