My children are descendants of both The Armstrong Clan and King Duncan I (Eryvine) 1034 AD. Shakespeare’s “Macbeth” is about the murder of King Duncan, as well as, the family that avenged Duncan's death – the Armstrongs. The Armstrongs earned their name and coat-of-arms by moving Birnam Wood (forest) to the castle to avenge the King’s death.  The Armstrongs cut down large trees and carried them upright for camouflage as they marched to reclaim Duncan's castle.  It appeared to Macbeth as though the forest was moving toward the castle.
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Duncan was a great, great grandfather of my father.  The Armstrongs are the family of my mother.
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Shakespeare: Act IV. Scene I<br>
Thunder. Third Apparition: a Child crowned, with a tree in his hand<br>
Third Apparition: Be lion-mettled, proud; and take no care; Who chafes, who frets, or where conspirers are: Macbeth shall never vanquish’d be until Great Birnam wood to high Dunsinane hill; Shall come against him.<br>
MACBETH: That will never be; Who can impress the forest, bid the tree; Unfix his earth-bound root? Sweet bodements! good! Rebellion’s head, rise never till the wood; Of Birnam rise, and our high-placed Macbeth; Shall live the lease of nature, pay his breath; To time and mortal custom.
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Shakespeare: Macbeth Act V. Scene III<br>
MACBETH: Bring me no more reports; let them fly all: Till Birnam wood remove to Dunsinane, I cannot taint with fear.<br>
Enter a Servant<br>
The devil damn thee black, thou cream-faced loon! Where got’st thou that goose look?<br>
Servant: There is ten thousand–<br>
MACBETH: Geese, villain?<br>
Servant: Soldiers, sir.<br>
MACBETH: Bring it after me. I will not be afraid of death and bane, Till Birnam forest come to Dunsinane.
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In Birnam Wood, Malcolm hatches a plan to take Dunsinane Castle by surprise: <br>
Act 5, Scene 4<br>
MALCOLM: Let every soldier hew him down a bough

<br>And bear't before him; thereby shall we shadow

<br>The numbers of our host and make discovery

<br>Err in report of us. 
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To Malcolm, having the soldiers move the trees of Birnam Wood up Dunsinane Hill is just a clever way to hide the army's numbers.