Wait....I thought it was canon that the Battle of Cheron was the last and decisive battle of the Earth/Romulan War which resulted in the Romulans giving up their territorial ambitions and staying behind the Neutral Zone. I'm pretty sure that it was mentioned that earlier in the war, things were going badly for Earth, to the point where the Romulans got pretty close to the Sol system. However, then Earth forces rallied back to push the Romulans out of 'Earth space'.
I found this quote on the Battle of Cheron from Memory Alpha:
I found this quote on the Battle of Cheron from Memory Alpha:
The Battle of Cheron was a pivotal battle that took place in 2160, between the Romulan Star Empire and an Earth/Andorian/Vulcan/Tellarite alliance. The outcome of the battle effectively ended the Romulan Wars, with the "humiliating defeat" of the Romulans. (ENT: "In a Mirror, Darkly, Part II" production art)
Even into the 24th century, the battle remained an intense embarrassment for the Romulans, which, according to Alidar Jarok, would be retributed by "the new leaders" on Romulus, who "vowed to discard the treaty and claim the Neutral Zone," with Nelvana III being the first step. (TNG: "The Defector")
http://memory-alpha.org/en/wiki/Battle_of_Cheron