What is the political situation in Scotland when Macbeth opens?
The early scenes of Macbeth reveal a great deal about the state of Scotland when the play opens. Act I, Scene 1 presents the audience with their first glimpse at the Weird Sisters, who are planning to meet with Macbeth at a later time. Given the character of the witches, this alone suggests a certain level of unrest within Scotland, as the Weird Sisters are at their worst when trying to sow the seeds of deceit among others. However, Act I, Scene 2 really sets the scene and reveals the true political climate of Scotland.
In Act I, Scene 2, King Duncan and his eldest son, Malcolm, happen upon a wounded captain, who tells them news of a battle taking place. Through exposition, the captain reveals that "[t]he merciless Macdonwald," whom he calls a rebel, has been "unseamed from the nave to th' chops" by Macbeth himself, thus quelling part of a rebellion within the country (1.2.11,24). However, Macbeth and Banquo were not simply fighting a minor rebellion. Instead, the Thane of Cawdor, referred to by King Duncan as "a gentleman on whom I built/ An absolute trust" had turned traitor and assisted Norway with an attempted invasion of Scotland (1.4.15-16). In other words, Scotland under King Duncan was fighting three enemies: Macdonwald and his rebellious forces, the Thane of Cawdor, and Norway's army. However, despite the odds against them, Macbeth and Banquo lead the Scottish forces to victory. Norway retreats, and the Thane of Cawdor is captured (and executed shortly thereafter), thus maintaining Duncan's rule, at least for the moment. This soon begins to change, of course, when the Weird Sisters meet up with Macbeth and sow the seeds of deceit within him as well.
A war between the Scottish army and invading Norwegian troops reinforced by some Scottish rebels, led by Macdonwald and the Thane of Cawdor, is taking place. Macbeth and Banquo are the captains leading Duncan's forces. The outcome of the battles will determine Scotland's future. Will it continue to be a sovereign nation with Duncan as king, or will it fall to the invaders?