This ship was assigned to the Romulan Empire's border with the Federation in the late 2270s decade, and rushed to the rescue of the Terran luxury starliner Vega under Captain J. Michael Reaves, which was carrying over 4,273 passengers, when it was seized by the Romulan Imperial Fleet vessel Avenger under subCommander tr'Annhwi. The Avenger, a Klingon K'hanakh-class frigate in Romulan service, tractored the Vega and escaped into Romulan space before the Valiant could get there. (TOS - Rihannsu novel: The Romulan Way)