I recently engaged in a war with an expensive-to-kill psychic warrior race. I prepared to face heavy losses, but my enemies deny me the satisfaction of mourning my soldiers' deaths. They didn't kill any but maimed them all (some still died of blood loss due to the don't-care-ness of their overlord, but I'm sure they did not mean it).

Now I have 3 (and counting) platoons of one-armed and one-legged men. The whole nation already knows that the enemy don't kill (so I can't just get rid of the useless veterans in secret and blame them).

How am I supposed to continue the invasion while wasting resources on these trivial matters?

**Edit**:
This is a European-like medieval world, no steam machine yet, but there are explosives, some rare magic left but mostly too unavailable to be useful.