The Border Legion was an army of Men from the Callahorn Borderlands that existed during the time of the Druid Allanon. The army was based primarily in Tyrsis, the fortified capital city of Callahorn. It played a crucial role in the Third War of the Races, protecting the otherwise defenseless Southland from the invading Northland armies.
Fifty years after the Third War of the Races, the Free Corps, a controversial unit of the Border Legion, assisted the Elves in the defense of Arborlon against the Demons during when the Ellcrys was failing. The Free Corps was later disbanded soon after the end of the monarchy in Callahorn.