Teresa of Portugal

Who was Teresa of Portugal?

Theresa of Portugal was Queen of Léon as the first wife of King Alfonso IX of León. She was the oldest daughter of Sancho I of Portugal and Dulce of Aragon.

Theresa was the mother to three of Alfonso's children—two daughters and a son, Ferdinand, who was the heir of the kingdom until his death in 1214—but when her marriage to Alfonso was declared invalid because they were first cousins, she returned to her home in Lorvão, Kingdom of Portugal. There, she founded a Benedictine monastery. Soon after, she converted the monastery into a large Cistercian convent, with over 300 nuns.

In 1230, Alfonso died after having several children with a second wife, Queen Berengaria of Castile. This second marriage was also annulled because Berengaria was Alfonso's first cousin once removed. With two invalidated marriages, there was dispute among the children as to who would inherit the throne. Theresa stepped in and allowed Ferdinand III of Castile, Berengaria's eldest son, to take the throne of León. After the succession dispute, Theresa returned to Lorvão and finally took her convent vows after years of living as a nun. She died in the convent on June 18, 1250 of natural causes.