Setting up a city populated by the spoils of war (slaves?)seems a little unlike any treatment of spoils of war (slaves?) I’ve ever heard of.
The Peloponnesian War was largely between Sparta and its “allies” on the one hand and Athens with its Delian League of “allies” on the other. After Sparta finally overcame Athens (and it’s easy to see that Athens’ demagogracy basically snatched defeat out of the jaws of victory), it was so used up that in its arrogance shot off its mouth a bit too much. Thebes, which was anti-Athenian and allied with Sparta had obviously prospered during the decades of the war, and Sparta’s rulers saw Thebes as the sole remaining serious threat.
The Thebans kicked the ever-loving snot out of them, then marched around freeing the hundreds of thousands of fellow Greeks the Spartans had enslaved over the previous generations, and helped them build walled towns and cities to keep the Spartans from ever being able to pull that crap again. Sparta turned into a flyspeck, of interest only to politicians like (e.g.) Hitler.
So, it’s not unheard of. :’)
Oops, and anyway, the Trojans carried off as war booty were put to work processing flax, which was a big industry, but the work was hard and unattractive to most. Better to have a work force without a choice.