The Earth-Romulan War, also known as the Romulan War(s), was a major interstellar conflict fought from 2156 to 2160 between the forces of United Earth and those of the Romulan Star Empire. Its conclusion, which was marked by an Earth/Andorian/Vulcan/Tellarite alliance decisively defeating the Romulans at the Battle of Cheron, led to the establishment of the Romulan Neutral Zone and immediately preceded the incorporation of the United Federation of Planets. (ENT: "In a Mirror, Darkly, Part II"; TOS: "Balance of Terror" )