The Vulcan-Romulan War was a violent conflict in Vulcan history between the followers of Surak and his philosophy, and his opponents, referred to as "those who marched beneath the raptor's wings," who later left Vulcan and settled the planet Romulus. This war lasted for a hundred years. (VOY episode: "Death Wish"; ENT episode: "The Forge")
- The Last Unicorn rpg books The Way of Kolinahr: The Vulcans and The Way of D'era: The Romulan Star Empire state that the Romulans fought the Vulcans through the use of a wormhole. The Vulcan-Romulan War might possibly have been this conflict rather then the actual battles that created the Sundering which forced the early Romulans to leave their home planet.
The war between the two races began in the Earth year 1270 and ended by 1370 which were in the Romulan years 901 and 1001. Instead of a rapprochement with their distant kin, the Romulans saw it as an opportunity to regain control of the distant homeworld of their species.
The conflict emerged when the wormhole that deposited the Romulans at their new homeworld of Romulus re-established itself linking Romulan territory to that of Vulcan space. At the time, both races lacked Warp drive technology and were entirely reliant on sub-light engines which meant that the Romulans were entirely reliant on the infrequent openings of the wormhole in order to send their invasion forces.
Though the Vulcans had embraced peace, they were not an entirely defenseless species and fought back against these aggressive invaders who did not identify themselves. The Romulan desire for victory meant that they detonated their warships before being captured which meant that the Vulcans never discovered who these attackers were and did not realize that these were their sundered kin.
The long distance war lasted a century due to the wormhole's unstable openings and each time the invaders were defeated by the tenacity of the Vulcan defenders as well as their well planned strategies. The conflict would finally end when the wormhole linking the two territories finally closed which prevented the Romulans from engaging in any further battles while the Vulcans would later become aware of the lengths the aggressors were capable of and knew that they able to destroy entire civilizations if necessary.
There would be some significant reprecussions for the Romulan Star Empire after the war. The Unification movement would see the conflict as a wasted opportunity at reuniting with their Vulcan cousins while the defeat of the Star Empire weakened the position of the Emperor of the Romulan Star Empire. This resulted in the rise of the Praetor of the Romulan Star Empire to a position more powerful than Emperor. (Last Unicorn RPG module: The Way of D'era: The Romulan Star Empire)
In a parallel timeline, the Romulans were victorious in the war and conquered their ancestral home world of Vulcan. However, the wormhole linking the two regions vanished once more meaning that the conquerors were cut off from Romulus. What followed was a return to the aggressive, war-like behavior that Surak had worked hard to remove with the establishment of a Vulcan empire that would began a period of aggressive expansion until it encountered the Romulan Star Empire. The two powers were hostile to one another as both saw themselves as the true inheritors of their heritage which brought about a tense period between the twin empires. (Last Unicorn RPG module: All Our Yesterdays: The Time Travel Sourcebook)