The Romulan War has been one of the most bloodiest and fiercest conflicts in interstellar history. The war was in fact unique in many ways. Interstellar travel and communications were still in their infancy when the war started. Starships rarely exceeded Warp 4, and had to rely on automated torpedoes for communication. Subspace radio was inefficient, weaponry was limited to short-range phasers and warp-capable fusion missiles.

Before the war, humans and Romulans did not have contact with each other. The first direct communications were by subspace radio when the truce that ended the war was negotiated in 2160. In addition, there was no personal contact of any kind. Ship-to-ship combat took place over distances of thousands of millions of kilometres, and colonies were either evacuated before attack of completely destroyed from orbit. United Earth intelligence had little success deciphering Romulan communications. In fact, what the enemy called themselves could not even be determined. They were given the name "Romulans" after the designation for the planet from which they were believed to have come. That the Romulans were an offshoot of the Vulcan race was not discovered until more than a century later.

After being defeated at the Battle of Cheron, the Romulans offered peace to Earth and its allies Andor and Tellar. The Romulan Neutral Zone was established as a buffer between the two powers. Until late in the 24th century, the zone remained one of the most heavily fortified borders in the known galaxy. Despite a certain degree of cooperation in the face of conquest by the Dominion, the Romulan Star Empire and the Federation remained hardened adversaries. Perhaps when a final peace is established, we will at long last gain a fuller understanding of why these two great cultures once went to war.

Sources for this information include TOS: "Balance of Terror", TNG: "The Neutral Zone", TNG: "The Defector" and DSN: "In The Pale Moonlight".