Instead, the two Different Races that were obliterated truly suffered annihilation. It's not that the Frank people and the Iberian People didn't sell Different Race slaves; the main issue was that no one was willing to buy them.
The Alien Coalition was just that, a coalition. It was one thing to pay a ransom if your own kind were captured, but for other Species, forget it!
No one was that saintly. To redeem a bunch of Half-Orcs and Cannibals, wouldn't that also mean setting aside a piece of land to sustain them?
As the war had progressed to this point, of the members within the Alien Coalition, only the arms-dealing Dwarf Race remained wealthy, still possessing considerable financial strength, while the rest were impoverished to the point of clinking destitution.
In the most recent dozen or so wars on the Continent, the Human Race managed to win more often than lose, not because of superior military strength, but because of victory in logistics.