From Memory Alpha"
The warbird design referred to as D'deridex-class, B-type warbird, or Warbird class was one of the largest and most powerful mainstays of the Romulan Star Empire. It served as the backbone of the Romulan fleet during the latter half of the 24th century.
The uncloaking of a warbird of this type in 2364, during an encounter with the USS Enterprise-D on the edge of the Neutral Zone, signaled the end to fifty-three years of Romulan isolation. (TNG: "The Neutral Zone") Over the next ten years, these warbirds, under the command of both the Romulan military and the Tal Shiar, participated in numerous encounters with Starfleet and the Dominion.
By 2374, they were prominently featured in the Dominion War, where they were instrumental in forcing the Dominion fleets back, time and again. The design saw action during the First and Second Battles of Chin'toka, as well as the final showdown of the conflict, the Battle of Cardassia. (DS9: "Tears of the Prophets", "The Changing Face of Evil")
At least four warbirds were used in the Battle of the Omarion Nebula, joined with at least twelve Cardassian Keldon-class cruisers in a combined fleet of twenty ships. The entire fleet was ambushed and destroyed by a fleet of 150 Dominion ships. (DS9: "The Die is Cast") At least seven warbirds were present in the Federation Alliance fleet at the Battle of Cardassia. One is known to have been destroyed and at least five survived. (DS9: "What You Leave Behind")
The D'deridex-class warbird was classified as a battle cruiser by Starfleet. Using a forced quantum singularity as a power source (see Black hole starship) and the latest in Romulan cloaking technology, the D'deridex was not only one of the most advanced vessels in the Romulan Star Empire, but also in the Alpha Quadrant. These warbirds were roughly twice as long as a Federation Galaxy-class starship with a lower overall maximum speed. (TNG: "The Neutral Zone", "Tin Man")