Isabella of Urgell explained

Isabella of Urgel (Aragonese: Isabel d'Urchel; died 1071) was Queen of Aragon; the only daughter of Ermengol III, Count of Urgell by his first wife Adelaide of Besalú.^{[1] [2]}

Isabella is mentioned in her brother Ermengol IV's testament.^{[3] [4]}

Isabella married in 1065 King Sancho Ramírez; by this marriage, Isabella was Queen of Aragon. The couple had one son, Peter I, Sancho's successor who left no surviving children. The couple divorced in 1070, and both remarried. Isabella may have become the second wife of William I, Count of Cerdanya in 1071.

Notes and References

1. There is a theory that Adelaide was the second wife of Ermengol.
2. Szabolcs de Vajay. Contribution à l'histoire de l'attitude des royaumes pirénéens dans la querelle des investitures: de l'origine de Berthe, reine d'Aragon et de Navarre, Estudios Genealógicos, Heráldicos y Nobiliarios, en honor de Vicente de Cadenas y Vicent (Hidalguía, Madrid, 1978.), pp. 375-402, 396.
3. Gesta Comitum Barcinonensium
4. Monfar y Sors (1853). Vol. I, p. 357. Zurita, J. (1669). Anales de la Corona de Aragon (Zaragoza); vol. I, lib. I, p. 31.