The Battle of Tong Vey was a legendary Klingon battle in which Emperor Sompek lead an army of ten thousand warriors against the city of Tong Vey. The army laid siege to the city for a long time before the city fell. Soon after, the warriors burned the city to the ground, and killed all survivors, soilders or otherwise.
Worf had a holoprogram of the battle aboard the USS Enterprise-D. He brought it to Deep Space 9, where he often used it in Quark's holosuites. He used the program a day before he commanded the USS Defiant in a convoy mission in the Pentath system. (DS9: "Rules of Engagement")