I'm very confused as to how and why I lost a

[Molog]

The enemy earth mother had 20 mr and was regenerating 55 hp a turn. She got attacked by 3 carrion elephants and 3 other carrion critters. The carrion elephants have only sleep vine attacks, which got ignored mostly and the rest did less than 55 damage a turn.

All your other units were unable to get to the earthmother because of bad pathfinding.

Fast forward a bunch of turns, your army routs and all your mindless units dissolve.