The Battle of Klach D'Kel Brakt was a decisive battle fought near the gaseous cloud Klach D'Kel Brakt, or "Briar Patch", between the rival Klingon and Romulan Empires in 2271. The battle was a memorable victory for the Klingons, who were led by Kor.
Nearly a century later, Kor re-enacted the battle on Deep Space 9's holosuites. Quark complained to Odo that Kor only paid for one hour, but had been in there for three "fighting the Battle of Klachdachbrach or some such thing over and over." From the sounds coming from within the holosuite, it seems that some or all of the battle was fought on the surface of a planet, or (far more likely) within the starships between boarding parties and defenders: with melee weapons. (DS9: "Blood Oath")