Afonso I

(born 1109/11, Guimarães, Port.—died Dec. 6, 1185, Coimbra) First king of Portugal (1139–85).

He defeated his mother to take the throne (1128), ruling first as a vassal of his cousin Alfonso VII of León but later securing Portuguese independence and gaining the title of king (1139). He defeated nearby Muslims and imposed tribute on them, then took Lisbon (1147) with the help of Crusaders. Afonso eventually extended Portugal beyond the Tagus River. He shared power with his son Sancho I and left him a stable, independent monarchy.