Sancho Garcés was an illegitimate son of King García Sánchez III and a concubine, born around 1038 and before his father married Stephanie. He was appointed tenant-in-chief of Uncastillo and Sangüesa and could have also been the Sancho Garcés who appears governing Ruesta, Surta, Autol, and Anguiano and Tobía in 1073. He had several siblings from his father's legitimate marriage, including King Sancho Garcés IV and Ramiro Garcés. He was also the brother of Mencía Garcés, wife of Fortún Ochoiz, another illegitimate daughter of the king, though it is not known if Sancho and Mencía shared the same mother. He died on 6 January 1083 with his brother Ramiro who led the army sent by Alfonso VI in what was to be known as the disaster or the treachery of Rueda, where many other nobles lost their lives, including count Gonzalo Salvadórez.
Marriage, descendants, and legend
He married Constanza before 25 November 1057 as indicated in a document from the Monasterio of San Prudencio de Monte Laturce when both confirm a sale made by his brother the king. They appear together, two weeks later, on 7 December 1057 confirming as domno Santio testis et uxor eius domna Constanza in the Monastery of Albelda. Constanza was previously considered to be a daughter of a Gonzalo Marañón. Nevertheless, medievalist Jaime de Salazar y Acha, based on the Chronica Naierensis, believes that Constanza could have been a daughter of a previous marriage of Stephanie, wife of King García Sánchez III, Sancho's father: Although this episode has been considered an unfounded legend, all the characters mentioned are documented and these events could have a basis of truth. In a charter dated 29 November 1074 recorded in the cartulary of the Monastery of Santa María de Otero de las Dueñas, King Sancho Garcés IV gives his brother some houses and land in Calahorra, declaring: vobis germano meo domno Sancio et uxori vestra vel germana mea domna Constancia, that is, "to you, my brother Sancho, and to your wife and my sister, doña Constanza". Sancho and Constanza had two children:
Some historians have identified Sancho Garcés with Sancho Macerátiz, tenant-in-chief in Oca. Sancho Macerátiz married Andregoto, a kinswoman of Andregoto Galíndez, queen of Navarre, and she appears as his widow in 1075 at San Millán de la Cogolla, accompanied by her children: Sancho Sánchez de Erro, Andregoto, Sancha, Jimena, and Velasquita. However, Sancho Garcés is attested with his wife Constanza in 1074, leaving no time for a remarriage to Andregoto and the birth of her five children within just a year, and furthermore Sancho Garcés was still living seven years after Andregoto appears as widow of Sancho Macerátiz, indicating that the two men were distinct. He has also on occasion been confused with his like-named half-brother, King Sancho Garcés IV.
