Battle of Tregh'bak

Prelude
On Stardate 20759.1 (2302.Q1), the USS Sarek under Captain T'Lorel, had just completed mapping the Ulysses System located in the Romulan Neutral Zone near Klingon and Romulan space when they suddenly encountered a Romulan task force entering the system. Tracking revealed the Romulan forces skirting the edge of the Neutral Zone before heading into Klingon space.

Concerned that this might be part of a plot to frame the Federation, the Sarek followed and was joined by the USS Courageous, with the Federation forces eventually determining the Romulans' destination as the Klingon colony world of Tregh'bak. The Sarek and Courageous managed to outrace the slower task force, and after discovery that the colony was woefully under-defended for the force coming their way, Captains Eaton and T'Lorel made the decision to join the defense. In addition, two K'tinga Light Cruisers arrived as reinforcements before the Romulan attack.

The Battle
The initial engagement between the Romulans and the joint Klingon/Federation defenses favored the latter, with a D7 Cruiser almost immediately focused down upon and disabled. The Romulans rallied in response as the two forces continued to trade fire, with three of the Klingon Birds-of-Prey destroyed in rapid succession. As the battle continued however, events worsened for the Romulan task force. Their second D7 Cruiser was disabled and one of their Birds-of-Prey heavily damaged, with little harm done to the Klingon and Federation forces in the process. At this point the Romulans made the decision to disengage.

The Aftermath
Unwilling to press farther in the face of the Klingon/Federation defenses, the Romulan fleet was forced to withdraw from the system, with the disabled D7 Cruisers abandoned and self-destructed, their escape pods collected by the Romulans as they fled. From the battle itself, the Federation learned of the existence of a new Romulan class of warbird and Captains Eaton and T'Lorel would both receive personal messages of commendation from the Klingon Chancellor for their "ferocity".

While the circumstances of the attack were unknown at the time, later contact with the Romulans revealed they were aiming to destroy the colony at Tregh'bak as it had been infected with the Ulith III Biophage. The Klingons were then forced to destroy the colony themselves.