I’m thinking, wouldnt an undead be, by definition of not having a brain or even being alive, be the perfect suicide assasin/canon fodder. But, you would need a method to keep the enemy side from recycling the boys a second time. If you dont, its like playing pingpong with a massive undead horde. A sport I’m sure many necromancers would enjoy playing. Also, hig lv clerics and paladins wold be able to, literally bless the rain, killing undead left and right.

On a side note, would the ghost of a soldier still want to fight? If so, the necromancer just got the posivility of more complex tactics and strategies, thanks to these ethereal aides.

“Divine intervention” can have so many varied meanings.

You can use the ol’reliable magical masterclass trick. Go to some nobles and tell them some random stadistic about how much can learning a cantrip help their sons to defend themselves in these hard times.