Because of the new weapons, skeletons and zombies weren't even qualified as cannon fodder.
The vampire of the baronet level was nothing but a target that could be taken out with one shot, as for the Wraiths that were immune to physical damage, they were unable to withstand the energy bullets transformed from qi.
Although the Black Warrior had strong melee capabilities, modernized armies never engaged in bayonet combat with the enemy, relying instead on various equipment to locate the enemy's area and then using powerful long-range firepower to obliterate them from kilometers away.
Unfortunately, while large troops could easily eliminate undead mixed squads, there were very few records of killing the core Wizard Wraiths.