Birnam Wood

The real Birnam Wood in Scotland

What Happens Here?

Or so much as it needs
To dew the sovereign flower and drown the weeds.
Make we our march towards Birnam.
Macbeth, Act VI, Scene ii

Macbeth shall never vanquished be until
Great Birnam wood to high Dunsinane hill
Shall come against him.
Macbeth, Act IV, Scene I

Macbeth learns from the witches that he will not die until Birnam Wood moves to Dunsinane Hill. After hearing this, Macbeth feels invincible and thinks that he will defeat the rebelling army. When it is time for battle, however, Macduff's, Malcolm's and Siward's army hides behind branches taken from Birnam and sneaks towards Dunsinane thus "moving" the woods towards the hill, making it possible for Macbeth to be killed.