Why did Alfonso VI recall El Cid after the Almoravids invaded Spain?

Following the Almoravid invasion of Spain in 1086, Alfonso VI suffered a crushing defeat at the Battle of Sagrajas. In response to this military crisis, the king suppressed his personal antagonism toward El Cid and recalled him from exile because he recognized the nobleman as the best general available to the Christians.1

Alfonso VI sought to utilize El Cid's renowned military expertise to bolster the defense of his kingdom against the North African invaders. Although El Cid's presence at the royal court was documented in July 1087, he eventually returned to Zaragoza and did not participate in the subsequent desperate battles that threatened the existence of Christian Spain, choosing instead to pursue his own political ambitions in Valencia.1