The Setlik system was a star system with at least four planets, proximate to both the Federation and the Cardassian Union. It was the site of several military engagements between those two powers during the Federation-Cardassian Wars, and later during the Dominion War.
A Federation colony was founded on Setlik III sometime during the mid-24th century. The Cardassians mistakenly believed this settlement to be the staging ground for an assault on their territory, and dispatched a strike force to destroy it. Over one hundred civilians were killed in this attack, later known as "The Setlik III Massacre."
The USS Rutledge was the first vessel to respond to the colony's distress calls. Among the casualties were the family of Rutledge Captain Benjamin Maxwell. The Rutledge crew -- among them Crewman Miles O'Brien -- were instrumental in saving the lives of the remaining colonists, and were decorated for their actions. (TNG episode: "The Wounded"; DS9 novelization: Emissary; DS9 episode: "Empok Nor")
In 2374, Dominion forces attempted to retake Setlik from the Federation. Starfleet was able to defend the system, but with heavy casualties and the loss of at least four ships. (SCE eBook: War Stories, Book 1)