Career
He drowned whilst attempting the Seventh Siege of Gibraltar. He was the son of Juan Alonso de Guzmán and of Beatriz de Castilla y Ponce de León, Lady of Niebla (died 1409), an illegitimate daughter of Henry II of Castile and of Beatriz Ponce de León. The Count drowned while besieging Gibraltar in October 1436.
This was the Seventh Siege of Gibraltar then the isthmus was under the control of the Spanish Moors.
