Aldamir was a Dunedan and the twenty-third king
of Gondor. He
lived at the time of the Kin-strife (the civil war in Gondor), and was
the second son of Eldacar, son of Valacar.
Aldamir was slain in
the in the battle at Umbar (against the Corsairs and Haradrim), and was
suceeded by his son, Vinyarion.
Vinyarion took the name
Hyarmendacil II, and avenged his father's death by taking Umbar from
the
Haradrim.
Reference: The Return of the
King