The date of the Cid’s birth is not known. However, it cannot be far from the middle of the eleventh century, certainly not more than ten to twenty years before the battle on the Carrion river (1037), in which Ferdinand I of Castile conquered the allied kings of Leon and Navarre, and Bermudo III, king of Leon, met his death. With this king, who left no descendants, the Visigothic dynasty came to an end, that dynasty which since Pelayo for three hundred years had carried on the struggles of Christian Spain against the superior force of the Moors, under the most variable circumstances, but ever with increasing success. The birth, as well as the youth and first warlike deeds of Rodrigo Diaz de Bivar, later called the Cid,[26] fall in that brilliant period when the kingdom of Spain first acquired a greater power by the union of Castile and Leon and attained a certain moral supremacy over Moorish Spain. In a battle led by the eldest son of the king Sancho, against Sancho of Navarre, the Cid conquered a knight of Navarre in single combat and thus received the surname Campeador, _i.e._, “Challenger.” With the death of Ferdinand I, however (1065), the scarcely established union fell asunder. In his will he divided his kingdom among his five children. [Sidenote: [1065-1085 A.D.]] Scarcely three years after his father’s death Sancho was in open fight with his brother Alfonso at Llantado and won a temporary, though not a decisive victory. On this occasion Rodrigo de Bivar was promoted to be “banner-bearer,” _i.e._, “chief commander” of Sancho’s troops. The brothers kept the peace for only three years. Eventually Sancho was assassinated. Since there was no suitable pretendant to the throne, the crown of Castile was finally offered to Alfonso, but only on condition that he take a solemn oath to the effect that he was not a party to Sancho’s death. Rodrigo Diaz de Bivar and eleven other knights administered this oath. The king at the same time was seized with a violent dislike towards the Campeador. Policy, however, advised him not to indulge this for the present, but to try to attach this powerful and influential Castilian to himself by showing him favour. He even gave him his cousin Ximena in marriage (the 19th of July, 1074).