Battle of Graus The Battle of Graus was a battle of the " Reconquista " , traditionally said to have taken place on 8 May 1063 . Antonio Ubieto Arteta , in his " Historia de Aragón " , re - dated the battle to 1069 . The late twelfth - century " Chronica naierensis " dates the encounter to 1070 . Either in or as a result of the battle , Ramiro I of Aragon , one of the protagonists , died . Ramiro ' s first attempt to take Graus , the northernmost Muslim outpost in the valley of the Cinca , took place in 1055 , probably in response to the defeat of García Sánchez III of Navarre at Atapuerca the year before ( 1054 ) , which placed Ferdinand I of León and Castile in a commanding position against Ramiro ' s western border and the Muslim Taifa of Zaragoza to his south . His first expedition against Graus failed , and in 1059 Ferdinand succeeded in extorting " parias " ( tribute ) from Zaragoza . Ramiro marched on Graus again in the spring of 1063 , but this time the Zaragozans had with them 300 Castilian knights under the " infante " Sancho the Strong and ( possibly ) his general Rodrigo Díaz de Vivar , better known as El Cid . The presence of the Cid at the battle is based on a single source , the generally reliable " Historia Roderici " , which alleges that he was the " alférez " of Sancho at the time . Considering the rarity of the Cid ' s name in the documents of the early 1060s , this is unlikely . The circumstances of the actual battle are obscure . Reinhart Dozy argued that Ramiro survived four months after the battle and that neither the Cid nor Sancho took any part in it . The " Fragmentum historicum ex cartulario Alaonis " records only that " occisus est a mauris in bello apud Gradus " ( he [ Ramiro ] was killed by the Moors in war near Graus ) , with no mentinon of the Castilians . The aforementioned " Chronica naierensis " contains an account generally , though not universally , regarded as a legend : that Sancho Garcés , an illegitimate son of García Sánchez III of Navarre , eloped with the daughter of García ' s wife , Stephanie ( probably by an earlier marriage ) , who was the fiancée of the Castilian " infante " Sancho , and that he sought refuge at the court first of Zaragoza , then later of Aragon . Sancho , to avenge the disruption of his marriage plans , marched against Ramiro and Zaragoza , and Ramiro died in the encounter near " the place called Graus " ( " loco qui Gradus dicitur " ) in 1064 or 1070 . According to the Arabic historian al - Turtūshī , Ramiro ( misidentified as " Ibn Rudmīr " , the son of Ramiro ) was assassinated by a Muslim soldier who spoke the Christians ' language and infiltrated the Aragonese camp . Charles Bishko , summarising the position of Pierre Boissonnade , explains how the battle of Graus gave impetus to the War of Barbastro of the next year : . . . the expedition against Barbastro is above all a French crusade , inspired by Cluny and launched through Cluny ' s persuasion by the papacy of Alexander II , the purpose of which is to preserve a hard - pressed Aragonese kingdom from imminent invasion and possible destruction at the hands of the Muslims , following Ramiro I ' s shattering defeat and death at Graus on 8 May 1063 . Graus , in this Hispanic prelude to the Palestinian " gesta Dei per Francos " , serves as an Iberian Manzikert , with King Sancho Ramírez — like the legates of the Emperor Alexius Comnenus at Piacenza — appealing in desperation for papal and Frankish succor . . . Graus was finally taken by Sancho Ramírez , Ramiro ' s successor , in 1083 .