In the final act of Shakespeare's Macbeth, Malcolm, one of the two sons of King Duncan, is one of the leaders in the battle against Macbeth. In Scene 4 of this act, which takes place in the countryside near Birnam wood, Malcolm tells Menteith and Siward to have their soldiers cut down boughs from the trees and carry those boughs in front of them. By this strategem, the army will disguise the number of soliders they have.
In the play's final scene, a messenger enters and tells Macbeth that he thought he saw Birnam wood moving. When Macbeth hears this, he knows that he is doomed. Earlier in the play, in Act 4, Scene 1, the Third Apparation had predicted that
When Macbeth had heard this prophesy, he considered himself invincible. How, he thought, could a forest possibly move? Malcolm's strategem, however, does make Birnam wood come to Dunsinane. : )