Not to hijack your thread, but I'll be running a much smaller undead unit battle, consisting of four graveknights: a leader antipaladin, 2 cavaliers and a magus myrmidarch. Also for backup, I have a gang of mohrgs that could be released after the fourth round of combat, in case the PCs are handling the undead knights too easily.
The setup for this is the party enters a chamber resembling the inner sanctum of a lawful good church with devas, archons, cherubs decorating the interior as statues and wall relief carvings. At the center of the chamber, nearest the altar is a statue of a deva, bearing a greatsword in it's two hands (+4 holy defender). The sword is 'cursed' to changing the alignment of the wielder to lawful good.
Currently the party consists of neutral alignments only, except 1 PC that has a good alignment. The goal is that the weapon is more powerful than any the PCs currently have, and is so desireable despite being of obvious good alignment (they don't realize it will change alignment by touching it). The sorcerer is the good member of the party, so unlikely to take the weapon herself. Touching/lifting the sword causing the alignment change is just to facilitate the antipaladin, who has no legal target for his smite (except the sorcerer), and I want one of the fighter tanks of the party to become a valid target, which is the point of including the alignment changing sword in the first place.
All the undead cavalry is hidden as embroidery on a large tapestry on the wall behind the sword altar, facing the PCs as if in a charge. When the sword is lifted from the altar, the altar, angel statues and wall relief crumble to dust, revealing the inner sanctum of an evil temple of black stone and demon statues and relief beneath the fallen angel relief. One round after the sword is lifted, the undead cavalry materializes and charges forth from the tapestry to begin the actual encounter.
This is going to be a nasty, evil encounter - bwahahaha!
Sorry, your thread got me thinking about my own weekend game... I don't have your problem though, I don't need to control the horde with one necromancer, rather the undead cavalry troop are intelligent undead working together to defeat the party that wields the holy defender sword.
I don't have a 'control' issue with my party of undead.