He next appears in scenes 5.4 and 5.6 as the troops enter Birnam Wood and Malcolm orders him and his father to lead the first battalion against Macbeth.
The "worldly governour" defeats the Christian warrior, and denies the analogy by saying "swords I smile at, weapons laugh to scorn, / Brandish’d by man that's of a woman born" (V. vii.
Young Siward is offering himself as champion of Christian good against the forces of darkness, and for Macbeth, his triumph over the boy is proof of his (mistaken) belief that no human can kill him.
Young Siward's Christian beliefs are echoed when his father hears of his death and is assured that his son has become "God’s soldier" because of his battle against evil.
Shakespeare alludes to the cowardice of Malcolme in the following words "You (worthy Uncle) Shall with my Cousin your right Noble Son Lead our first Battle."