War of Barbastro The War of Barbastro ( also known as the Siege of Barbastro ) was an international expedition , sanctioned by Pope Alexander II , to take the Spanish city of Barbastro from the Moors . A large army composed of elements from all over Western Europe took part in the successful siege of the city ( 1064 ) . The war was part of the Reconquista , but in its international and papal character it presaged the Crusades of the next two centuries . Ramón Menéndez Pidal famously described the expedition as " a crusade before the crusades " . Expedition . Alexander II first preached the Reconquista in 1063 as a " Christian emergency . " It was also preached in Burgundy , probably with the permission of participation of Hugh of Cluny , where the abbot ' s brother , Thomas de Chalon , led the army . Certainly zeal for the crusade spread elsewhere in France , for Amatus of Montecassino notes that the " grand chivalry of the French and Burgundians and other peoples " ( " grant chevalerie de Francoiz et de Borguegnons et d ' autre gent " ) was present at the siege . Thus , a large army , primarily of Frenchmen and Burgundians , along with a papal contingent , mostly of Italo - Normans , and local Spanish armies , Catalan and Aragonese , was present at the siege when it began in 1064 . The leader of the papal contingent was a Norman by the name of William of Montreuil . The leader of the Spaniards was Sancho Ramírez , King of Aragon , whose realm was greatly threatened by the Moors to the south . The largest component , the Aquitainian , was led by the Duke Guy Geoffrey , whom one historian calls the " Christian generalissimo " . Though the makeup of this grand army has been subject to much dispute , that it contained a large force of Frankish knights is generally agreed upon . The duke of Aquitaine led the army through the Pyrenees at Somport . He joined the Catalan army at Girona early in 1064 . The entire army then marched past Graus , which had resisted assault twice before , and moved against Barbastro , then part of the taifa of Lleida ruled by al - Muzaffar . The city was besieged for forty days until it surrendered according to both Muslim and Christian sources . Consequences . Terms were given by the Christians to spare the lives of the Muslims and respect their properties , but the pact was quickly broken . Another source tells us that the garrison offered to surrender their property and families in exchange for letting them leave the town , and so it was agreed with the besiegers . However , the Crusaders didn ' t honour the treaty and killed the soldiers as they came out . Crusade soldiers plundered and sacked the city without mercy . Thousands of Muslims , i . e . residents and what little garrison remained , were massacred ( reportedly 50 , 000 ) and the victors divided an enormous amount of booty . The Andalusian Muslim jurist Ibn ' Abd al - Barr was among the witnesses of the fall of Barbastro . He described the aftermath as follows : What can be your opinion , O Muslims , when you see mosques and oratories , that once were witness to the recitation of the Qur ’ ān and the sweetness of the call to prayer , immersed in polytheism and slander , loaded with bells and crosses in place of the followers of the Merciful : imāms and pious men , vergers and muezzins . . . are dragged away by the infidels like animals for sacrifice , they are brought to the butcher , they prostrate themselves humbly in the mosques which are then burnt and reduced to ashes while the infidels laugh and insult us , and our religion wails and weeps . Not only that , the plight of the women seem to have been especially tough as a consequence of the siege and victory of the crusaders . During the siege an indefinite large amount died of thirst related diseases and were subjected to degrading treatment after victory , converting them into servant and sex slaves , or sometimes even exposing them to the torture of their husbands . The crusaders made off with a lot of booty . The " Kitab al - Rawd al - Mitar " records the capture of a good many Saracen girls and Saracen treasures . Armengol III of Urgel was given the lordship of the city . In 1065 , in a counterattack , the Moors easily retook the city and undid all the crusaders ' work , massacring the small garrison . Thibaut , the Burgundian leader , died , possible of wounds received on campaign , while returning to France after the loss of the city in 1065 . Historiography . Historian Reinhart Dozy first began a study of the War in the mid - nineteenth century based on the scarce primary sources , mainly Amatus and Ibn Hayyan . Dozy first suggested the participation of a papal element based on Ibn Hayyan ' s reference to the " cavalry of Rome . " Subsequent historiography has stressed the Cluniac element in the War , primarily the result of Ferdinand I of León ' s recent attempts to introduce the Cluniac reform to Spain and inspired by the death of Ramiro I of Aragon following the failed Siege of Graus . This interpretation has been criticized in more recent decades , especially the papal connection and Italian involvement . It has been suggested that Alexander was preoccupied with the Antipope Cadalus at the time and did not preach a plenary indulgence for warriors of the Reconquista until the 1073 campaign of Ebles II of Roucy . It has also been theorized that it was not William of Montreuil , but Guy Geoffrey , who was the " Roman " leader implied by Ibn Hayyan .