Alfonso was the only son of King Ferdinand II of León and Urraca of Portugal. Though he took a part in the work of the reconquest, this king is chiefly remembered for the difficulties into which his successive marriages led him with the Pope. He was first married in 1191 to his cousin Teresa of Portugal, who bore him two daughters, and a son who died young.
The marriage was declared null by the Pope; however, Alfonso paid no attention until he was presumably tired of his wife. His next step was to marry his second cousin, Berenguela of Castile, in 1197. For this act of contumacy, the king and the kingdom were placed under interdict.
The Pope was, however, compelled to modify his measures by the threat that, if the people could not obtain the services of religion, they would not support the clergy, and that heresy would spread. The king was left under interdict personally, but to that he showed himself indifferent, and he had the support of his clergy. Berenguela left him after the birth of five children, and the king then returned to Teresa, to whose daughters he left his kingdom in his will.
Alfonso's children by Teresa of Portugal were:
His eldest daughter, Sancha, was engaged to her cousin King Henry I of Castile, but Henry died in 1217 before the marriage could be solemnized. Wanting to disinherit his eldest son, Fernando, King Alfonso invited John of Brienne to marry his daughter Sancha and thus inherit the Leonese throne. However, Queen Berenguela convinced John of Brienne to marry one of her daughters instead. Though she was the nominal heiress on her father's death in 1230, Sancha was easily set aside by Berenguela and Fernando. Sancha became a nun at Cozollos, where she died in 1270; she was later beatified. Her sister Dulce-Aldonza spent her life with their mother in Portugal.
Alfonso's children by Berenguela of Castile were:
Alfonso also fathered many illegitimate children:
Alfonso's children by Aldonza Martínez da Silva (daughter of Martim Gomes da Silva & Urraca Rodrigues and subsequently wife with issue of Diego Froilaz, Conde de Cifuentes, had issue):
Alfonso's child by Inés Iñíguez de Mendoza (ca. 1180-) (daughter of Lope Iñiguez de Mendoza, 1st Lord of Mendoza (ca. 1140-1189) and wife Teresa Ximénez de los Cameros (ca. 1150-)):
Alfonso's child by Estefánia Pérez de Limia, daughter of Pedro Arias de Limia and wife, subsequently wife of Rodrigo Suárez, Merino mayor of Galicia, had issue):
Alfonso's children by Maua, of unknown origin:
Alfonso's children by Dona Teresa Gil de Soverosa (ca. 1170-) (daughter of Dom Gil Vasques de Soverosa & first wife Maria Aires de Fornelos):
Alfonso's other illegitimate child, mother unknown: