The extent and power of the realm Atanatar had inherited earned him the title Alcarin ('Glorious') but he did little to maintain its strength, and nothing to expand its influence. Already during Atanatar's reign, then, Gondor began to stagnate. There is some evidence to suggest that Gandalf first visited Gondor during this period, earning the name Incánus from the Gondorians.
Atanatar II ruled Gondor for seventy-seven years, during which the wealth and power created by his father slowly began to wane. Atanatar was succeeded by his eldest son, who ruled as Narmacil I, but Narmacil had no children and was succeeded in turn by his brother, Atanatar's younger son Calmacil.
The date of Atanatar's birth appears only in The History of Middle-earth volume 12, The Peoples of Middle-earth. It cannot therefore be considered completely reliable.