Macbeth is a Jacobean play, through and through.
It celebrates the accession of James VI & I, and his descent through a true line of Scottish kings, foreseen to “stretch out to the crack of doom.” In the vision summoned by the witches to appall Macbeth, the distant heirs of Banquo carry “treble scepters”: emblems of the kingship of England, Ireland, and Scotland. Elizabeth I did not rule Scotland; her rival Mary, James’s mother did. He sought the union of his realms.
Macbeth alludes to the policies and slogans of his reign: Concord, Peace, and Unity. Malcolm feigningly protests that he would “pour the sweet milk of concord into hell, /Uproar the universal peace, confound / All unity on earth.”