In 2366, the USS Enterprise-D was contacted by the Bortas when Captain Picard requested reinforcements prior to entering the Romulan Neutral Zone to investigate a potential Romulan military base on Nelvana III. This show of force prevented a confrontation with Tomalak. (TNG: "The Defector")
The Bortas was later Chancellor Gowron's flagship around and during the Klingon Civil War in 2367-68. It came to accompany the Enterprise as it arrived to Qo'noS for Gowron's ascension. Later, while Worf was on board, the ship took heavy damage during a surprise attack by ships loyal to the House of Duras at the beginning of the war, but drove off the attackers with assistance from the IKS Hegh'ta. After Worf resigned from Starfleet to fight alongside Gowron, he was initially assigned as tactical officer aboard the Bortas. (TNG: "Redemption")
In late 2369, Gowron traveled aboard the Bortas to rendezvous with the Enterprise-D when the latter ship was transporting the supposed reincarnation of Kahless the Unforgettable to Qo'noS. (TNG: "Rightful Heir")
|IKS Bortas • IKS Drovana • K'mpec's attack cruiser • IKS Maht-H'a • IKS Qu'Vat • IKS Toh'Kaht • IKS Vor'nak • Unnamed|
Background information Edit
In the Klingon language, bortaS means "revenge." According to the script for "Redemption", the pronunciation for this word was "bor-TAS".  An early draft of the script for "The Defector" mentioned the name Patakt, which later changed to Bortas by the time of the final airing of the episode.
The Starships RPG sourcebook gives its registry as IKC-11546.
According to Star Trek: Star Charts (p. 64) and Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385"), there was a star system named Bortas, which might be the possible origin for the name of this starship, in the Beta Quadrant. The system's primary was a G-class star. It was the site of a historic battle.