In 975, Sancho was defeated by the Moors at San Esteban de Gormaz and it has been suggested that he was captured at the Battle of Estercuel that year.
Pada tahun 975, Sancho dikalahkan oleh bangsa Moors di San Esteban de Gormaz dan dijelaskan bahwa ia ditangkap di Pertempuran Estercuel tahun itu.