The Star Trek encyclopedia says that the USS Intrepid Excelsior class NCC 38907 was the first ship to respond to the Klingon distress calls when the Khitomer outpost was under attack by the Romulan in 2346 ("sins of the Father") (TNG)
But the Enterprise C was there before and defend it self against 4 Romulan warbird.
Enterprise C The fourth Federation starship to bear the name Enterprise, an Ambassador-class vessel registry number NCC-1701 C was lost and presumed destroyed near Narendra III in 2344. In that year, this ship commanded by captain Rachel Gerrett, responded to a distress call from the Klingon outpost on Narendra III. The outpost was under a massive Romulan attack. During the battle, a torpedo explosion opened a temporal rift, and the Enterprise C was sent some 22 years forward in time. This proved to be a focal point in history. With the Enterprise C gone from "normal" timeline, an alternate timeline was formed, in wich the Federation and the Klingon Empire engaged in an extended war. The Federation was near defeated by 2366, when the Enterprise C emerged from the rift, encountering the Enterprise D. It was soon realized that the Enterprise C had to return to its proper time if history was to be restored and the terrible war with the Klingon was to be averted. The tragedy of the war was emphasized when a Klingon attack resulted in the death of Captain Garrett, after which Enterprise C officer Lieutenant Richard Castillo agreed to assume command of his ship, and return in to 2344. Enterprise D officer Natasha Yar (alternate), who was still alive in this timeline, volunteered to return with Castillo to help defend Narendra III against the Romulans. All Enterprise C personnel understood that returning to the pas was a virtual suicide mission because of the intensity of the Romulan attack on Naredra III. Once the Enterprise C return through the riff, the time flow returned to normal, and history was restored to its proper shape.
What I don't understand is the Enterprise C was the only ship to defend Narendra III ? Two years after that the Romulan attack the Khitomer outpost. What was the Intrepid doing there? Its in Klingon territory no? The answer a distress call from the outpost. How many Romulan ship where there to attack the outpost? What are the other ship who respond to the distress call? No Klingon ship? Why did the keep Worf with them instead of returning him to the Klingon?