[MaxWilson]

But you also said you were summoning tons of undead during the battle, presumably with Raise Skeleton and Raise Dead. I'm 80% sure killed skellies and zombies still count toward the 75% limit, so theoretically if you had 1000 units, then you summoned another 3000 skeletons during the course of the battle, and LA Man killed all those skeletons, your army would auto-rout because 75% casualties had been taken. I don't know how plausible it is that your guys would have summoned 3000 skeletons, though.

The turn route feature is not moddable. Modding is focused on altering unit/nation/spell stats, not changing the basic rules of the game.

You can still go with the vast hordes of undead if you like; just cast Rigor Mortis at the start of the battle and it should all work just fine. Your undead hordes are immune to it, but Man's troops should quickly fatigue into unconsciousness so your troops can slaughter them, and once they hit 200 fatigue they start taking physical damage instead of fatigue (although of course since they're unconscious they also recover 5 fatigue per round too). They should all be dead well before the auto-route limit.

-Max