Carl's standing instructions on enemy captives: convert the NPCs, and kill and keep the mercenaries.
After seven enemy scouts are captured or killed at the Southern Front — including a Saccathian Prince Saboteur who flooded an escape tunnel with an Instant River Scroll — Carl sends out orders.
If an enemy can be captured and kept alive but unconscious, that is to be done. Dungeon-Born NPCs and Mercenaries born outside the dungeon are to be separated, because there are spells that can turn the NPCs to the crawler side. The mercenaries, Carl notes flatly, have another purpose: if any give trouble, or if holding them isn't feasible or safe, kill them, loot them under the Safe-Looting Protocols, keep the body, and report it to a superior officer, who passes the information back to base where crawlers who prefer to stay out of direct fighting keep track of the big picture.
Carl's army-wide policy on captives, hinting at a use for mercenary corpses beyond looting.