Use Margaret as bait

You turn to the wood elf you trusted before and tell him, "Take Elizabeth and Rachael and run to the same spot as before... but leave Margaret with me."

Her eyes grow wide with fear, and she asks, "What?! Why me...?"

"Because you are my ****... and you do as I please..." You reply angrily at her outburst.

"But... so is..." Margaret stammers before you stare her down, quickly silencing her.

The girls are taken away, and your troops quickly take their positions. As she leaves, Elizabeth and Rachael look back at you. The sight of your rugged looks, dressed in your armor while leading your troops, makes them smile.... glad to have found a man more than worthy of their affection.

As you thought, you see catapults rain fireballs down from the sky. Lucky for you, they still believe you are in the same camp as last night... the rounds falling harmlessly away from you.

After three rounds of fire from the catapults, they send what looks like over a thousand troops up the hill. You smile as your plan comes together, so you use Margaret as planned... You quickly push her out, ordering her to wander in front of the lead group of troops. You know the front of their line is composed of their most expendable men, so you figure their least experienced and disciplined troops must be there. Margaret's naked form quickly catches their eye, and they laugh as she chases her, pushing each other to be the first to claim her. She manages to pull over two hundred with her directly toward your trap. Regrettably, you were hoping she would pull more... but you figured what she did manage to pull was better than nothing. As soon as she is out of sight, you have the mages roll a fog in and drop 5 more trees, only killing 25 but spreading the army in 5 chunks of 150 and one chunk of 250. You then order your archers to fire at will, creating a diversion that allows 10 high elves disguised as the enemy to join their ranks. When the archers cease-fire, they begin screaming imposter at the top of their lungs, wildly swinging their swords, killing a few of the leaders before the archers fire again, allowing them to sneak out in the confusion.

Once the soldiers break formation and lose all sense of cohesion, you sit back and watch the havoc take place. The soldiers begin calling each other imposters and killing each other without even considering confirming their suspicions. Once a soldier wetness another killing someone, they call an imposter on him and end him themselves. In order to get away, some soldiers begin to climb over the giant trees. But when the enemy sees them flee, they assume they are hostile and pull them down to the forest floor, hacking them to pieces. The slaughter continues until their captains finally regain control. However, they have already lost 500 troops between your arrows and their own killing.

Then the last part of your plan comes into play...