In Shakespeare's play The Tragedy of Macbeth, the four men who lead the army against Macbeth in Act V Scene VI are Macduff, Old Siward, Malcolm, and Young Siward.

Old Siward is a general in the English forces. In Act V, Scene II, readers learn from Menteith that Old Siward is Malcolm's uncle.

"The English power is near, led on by Malcolm,
His uncle Siward and the good Macduff."

"Whither indeed, before thy here-approach,

Old Siward, with ten thousand warlike men,

Already at a point, was setting forth."

"Be lion-mettled, proud, and take no care

Who chafes, who frets, or where conspirers are.

Macbeth shall never vanquished be until

Great Birnam Wood to high Dunsinane Hill

Shall come against him."

Three significant men appear in Act Five, Scene 6, of Macbeth to lead their armies against the tyrant. Malcolm, Old Siward, and Macduff enter the scene carrying branches from Birnam Wood as they approach Dunsinane castle, which correlates to the prophecy. Malcolm instructs the men to throw down their branches before ordering Old Siward and his son, Young Siward, to attack Macbeth's castle first. Malcolm then tells the men that he and Macduff will follow them and finish the job. Young Siward is the fourth man in the group and helps his father lead an army against Macbeth. In the next scene, Young Siward is the first notable opponent to meet Macbeth and dies at his hands, which only builds Macbeth's confidence and belief that he cannot be harmed by any man born of a woman.

MacDuff, Malcolm, Lennox and old Siward are specifically mentioned as marching on Dunsinane, but Rosse and other thanes are also implicitly a part of their army.