García Sánchez III, was king of Navarre from 1035 to 1054. He was the eldest legitimate son and heir of Sancho the Great, born November 1016, and he succeeded his father to the crown of Navarre, becoming feudal overlord over two of his brothers: Ramiro, who was given lands that would serve as the basis for the kingdom of Aragón; and Gonzalo, who received the counties of Sobrarbe and Ribagorza. Likewise, he had some claim to suzerainty over his brother Ferdinand, who under their father had served as Count of Castile, nominally subject to the Kingdom of León but brought under the personal control of Sancho III.
In 1037, Ferdinand requested García's aid against his brother-in-law, Bermudo III of León, at the Battle of Tamarón near Pisuerga. The two brothers defeated Bermudo, who died in battle, the final king of the male line of Peter of Cantabria, and Ferdinand succeeded in León.
By aiding Ferdinand, García received his brother's favour and, in a repartition of Castile, he expanded Navarre to the Bay of Santander, incorporating the entire Basque Country.
Soon he was confronted by his brother Ramiro at Tafalla (1043) and defeated him, but this victory resulted in the effective independence of Ramiro.
García was one of the Christian kings to profit greatly from the weakened taifa kingdoms that arose through the disintegration of central control by the Caliphate of Córdoba. In 1045, he conquered Calahorra.
Relations eventually soured with Ferdinand and war broke out between the fraternal kingdoms, García dying in the Battle of Atapuerca, September 15, 1054.
His nickname comes from his foundation of the monastery of Santa María la Real of Najera.
He was married, in 1038, to Estefanía, daughter either of Bernard-Roger, Count of Bigorre or his brother-in-law Ramon Borrell, Count of Barcelona (her dowry was the Cameros), and they produced eight children (four sons, four daughters):
Sancho "El de Peñalén", king of Navarre, married Placencia
Ramiro (d.1083), lord of Calahorra
Ferdinand Garcés, lord of Bucesta
Raymond Garcés "the Fratricide" (Ramón el Fratricida), lord of Murillo and Cameros
Ermesinda Garcés, married Fortún Sánchez de Yarnoz
Mayor Garcés
Urraca Garcés (d.1108), married Castilian count García Ordóñez
Jimena
He also had illegitimate issue:
Sancho Garcés, lord of Uncastillo and Sangüesa, jure uxoris-by right of his wife, Constanza. He was grandfather of García Ramírez, king of Navarre
Mencia Garcés (d.1106), wife of Fortún Ochoiz
After García's death, Estefanía is said to have remarried to Roger de Tosny, a Norman adventurer, although this marriage is not documented and seems unlikely since she does not mention such marriage when she executed her will in 1066, naming all her children and making several donations to the monastery founded by her late husband the king. Estefanía may have been a widow at the time of her marriage to García. The Chronica Naierensis tells of the marriage of an illegitimate son of García (presumed to be Sancho) to his stepsister, a daughter of Estefanía by a former husband