Infante don SANCHO de Castilla, son of ALFONSO VII "el Emperador" King of Castile and León & his first wife Berenguela de Barcelona (1134-Toledo 31 Aug or 1 Sep 1158, bur Toledo, Cathedral Santa María). The De Rebus Hispaniæ of Rodericus Ximenes names "Sancium et Fernandum, Elisabeth et Beatiam" as the children of "Aldefonsi Hispaniarum Regis" and his wife "Berengariam"[623]. The Chronicle of Alberic de Trois-Fontaines names "rex Sanctius" as son of "rex Aldefonsus Hispanie imperator"[624]. Don Gutierre Fernández de Castro was named his tutor from his birth[625]. "Santius et…Fredinandus et Garsias filii ymperatories" confirmed the charter dated 12 Sep 1142 under which Alfonso VII King of Castile donated "uillam…Taranna" to "Martino Didaci"[626]. "Adefonsus imperator Hispanie…cum uxore mea Berengaria" donated "ecclesiam sancti Vincentii de Salamantica" to Cluny by charter dated 29 Oct 1143, confirmed by "Sancius imperatoris major filius…"[627]. "Sancius et…Fernandus et Garsias filii imperatoris…" confirmed the charter dated 19 Aug 1146 under which Alfonso VII King of Castile donated "ecclesiam…sanctam Mariam de Uelerda" to "Martino Didaci"[628]. Called King of Nájera from 1149[629]. "Rex Sancius…domni Adefonsi imperatoris filius" donated property to the abbey of Silos by charter dated 14 Mar 1155, confirmed by "Regina domna Blanca uxor regis, Comes Almanricus, Comes Poncius maiordomus regis, Fortun Lopiz de Soria…"[630]. He succeeded his father in 1157 as SANCHO III "el Deseado" King of Castile and Toledo. He negotiated a peace treaty with his brother at Sahagún 1158 to avoid further family conflicts which had until then marred the history of Castile. The Chronicon Burgense records the death in 1158 of "Rex Sancius filius Imperatoris"[631]. The Anales Toledanos record the death "el postrimer dia Dagosto" in 1158 of "el Rey D. Sancho fillo del Emperador"[632]. The Annales Compostellani record the death "Kal Sep" in 1158 of "Sancius filius Aldephonsi Imperatoris"[633].
m (Calahorra 30 Jan 1151) Infanta doña BLANCA de Navarra, daughter of GARCÍA VI "el Restaurador" King of Navarre & his first wife Marguerite de l'Aigle ([1137]-12 Aug 1156, bur Nájera, Cathedral Santa María de Real). The Annales Compostellani record the death "II Id Aug" in 1146 of "Regina Branca mater istius Aldefonsi Regis Castellæ…filia Garsiæ Regis Navarræ"[634], although the year is clearly incorrect. "Rex Sancius…domni Adefonsi imperatoris Hyspanie filius" donated "[monasterium] beate Marie de Naigara" to Cluny by charter dated 30 Aug 1156 "pro remedio…mulieris mee…regine domne Blanche quam in Jagarensi ecclesia sepelire feci"[635].
King Sancho III & his wife had two children
http://fmg.ac/Projects/MedLands/CASTILE.htm#_Toc273596053