He became progressively more involved to Leonese court politics, eventually serving Alfonso VII as a count and having a marriage arranged to the king's half-sister.
His father was Guy de Conflans, castellan of Prény, and his mother was Hildiarde (or Hodiarde), daughter of Thibaud, count of Reynel, and Ermentrude.
[2][3] This Ermentrude was the daughter of Hilduin IV, Count of Montdidier and Lord of Ramerupt, and Alice, heiress of the County of Roucy.
[4] Ermentrude's brother, Count Ebles II of Roucy, campaigned in Spain in 1073, and their sister, Felicia, married King Sancho of Aragon, father of Alfonso the Battler.
[2][4][5] Beltrán arrived in Castile in the entourage of his cousin, Alfonso of Aragon, who appointed him governor of Logroño in June 1112[3] and of Carrión de los Condes in 1113,[6] charges he was still executing as late as 1125.
[7] A document dated to 27 October 1112 and preserved in the Gallican Cartulary of Valpuesta, records that Beltrán was count in Término and Pancorbo.
[15] The synod also made bishops Hugh of Oporto and Pascal of Burgos responsible for the satisfaction of the monks' claims against the burghers and for the return of the latter to their homes.
[17] On 8 October Beltrán and Pedro Fróilaz de Traba witnessed a charter of the young heir and co-regent, Alfonso VII, for the monastery of Sahagún.
Early in Alfonso's reign, at least from June 1126, Beltrán was governing a new fief, Abia de las Torres.
She was the widow of Count Gómez González, who had died leading the queen's forces against the Aragonese at the Battle of Candespina on 26 October 1111.
His second wife was Elvira Pérez, illegitimate daughter of Queen Urraca and Pedro González de Lara, who is first mentioned in a document of 1117, her parents probably having been lovers only from 1112.
[23] At the time of their marriage, which had taken place by 1130, Alfonso granted Elvira the vills of Nogal and Olmillos, located on the Way of Saint James in northern Castile.
[23] According to the aforementioned Genealogy of Foigny, written about 1161, Beltrán "had by a daughter of the emperor of Spain children of both sexes" (quia de filia imperatoris Hispanie habuit liberos utriusque sexus), but it does not name them.
[32] Beltrán's posthumous reputation can be gauged from line 3004 of the Poema de mio Cid, written towards the year 1200.
There he is placed in the second tier of nobility, immediately beneath Alfonso VI, Henry of Portugal, and Raymond of Galicia, and beside Fruela Díaz.