Alfonso I (1073/1074 – 8 September 1134), called el Batallador, the Battler or the Warrior, was the king of Aragón and Navarre from 1104 until his death in 1134. In 1109, he took up the title of his father-in-law: Imperator totius Hispaniae. He was the second son of King Sancho Ramírez and successor of his brother Peter I. Alfonso the Battler won his greatest successes in the middle Ebro, where he expelled the Moors from Zaragoza in 1118 and took Egea, Tudela, Calatayud, Borja, Tarazona, Daroca, and Monreal del Campo. He died in September 1134 after an unsuccessful battle with the Moors at the siege of Fraga.
During his brother's reign, he participated in the taking of Huesca (the Battle of Alcoraz, 1096), which became the largest city in the kingdom and the new capital. He also joined El Cid's expeditions in Valencia. His father gave him the lordships of Biel, Luna, Ardenes, y Bailo.
A series of fortunate deaths put Alfonso directly in line for the throne. His brother's children, Isabel and Peter (who married María Rodríguez, daughter of El Cid), died in 1103 and 1104 respectively.
Alfonso's late marriage and his failure to remarry and produce the essential legitimate heir that should have been a dynastic linchpin of his aggressive territorial policies have been adduced as a lack of interest in women. Ibn al-Athir (1166-1234) describes Alfonso as a tireless soldier who would sleep in his armor without benefit of cover, who responded when asked why he did not take his pleasure from one of the captives of Muslim chiefs, responded that the man devoted to war needs the companionship of men not women.
In 1122 in Belchite, he founded a confraternity of knights to fight against the Almoravids. It was the start of the military orders in Aragón. Years later, he organised a branch of the Militia Christi of the Holy Land at Monreal del Campo.
In 1118, the Council of Toulouse declared it a crusade to assist in the reconquest of Zaragoza. Many Frenchmen consequently joined Alfonso at Ayerbe. They took Almudévar, Gurrea de Gállego, and Zuera, besieging Zaragoza itself by the end of May. On 18 December, it fell and the forces of Alfonso occupied the Azuda, the government tower. The great palace of the city was given to the monks of Bernard. Promptly, the city was made Alfonso's capital. Two years later, in 1120, he defeated a Muslim army intent on reconquering his new capital at Cutanda. He promulgated the fuero of tortum per tortum, facilitating taking the law into one's own hands, and forced the Muslim population of the city (greater than 20,000) to move to the suburbs.
In 1119, he retook Cervera, Tudejen, Castellón, Tarazona, Ágreda, Magallón, Borja, Alagón, Novillas, Mallén, Rueda, Épila and repopulated the region of Soria. He began the siege of Calatayud, but left to defeat the army at Cutanda trying to retake Zaragoza. When Calatayud fell, he took Bubierca, Alhama de Aragón, Ariza, and Daroca (1120). In 1123, he besieged and took Lérida, which was in the hands of the count of Barcelona. From the winter of 1124 to September 1125, he was on a risky expedition to Peña Cadiella deep in Andalusia.
In the great raid of 1125, he carried away a large part of the subject Christians from Granada, and in the south-west of France, he had claims as usurper-king of Navarre. From 1125 to 1126, he was on campaign against Granada, where he was trying to install a Christian prince, and Córdoba, where got only as far as Motril. In 1127, he reconquered Longares, but simultaneously lost all his Castilian possessions to Alfonso VII. He confirmed a treaty with Castile the next year (1128) at Támara which fixed the boundaries of the two realms.
At the siege of Bayonne in October 1131, three years before his death, he published a will leaving his kingdom to three autonomous religious orders based in Palestine and politically largely independent on the pope, the Knights Templars, the Hospitallers, and the Knights of the Holy Sepulchre, whose influences might have been expected to cancel one another out. The will has greatly puzzled historians, who have read it as a bizarre gesture of extreme piety uncharacteristic of Alphonso's character, one that effectively undid his life's work. Elena Lourie (1975) suggested instead that it was Alphonso's attempt to neutralize the papacy's interest in a disputed succession— Aragon had been a fief of the Papacy since 1068— and to fend off Urraca's son from her first marriage, Alphonso VII of Castile, for the Papacy would be bound to press the terms of such a pious testament. Generous bequests to important churches and abbeys in Castile had the effect of making the noble churchmen there beneficiaries who would be encouraged by the will to act as a brake on Alphonso VII's ambitions to break it— and yet among the magnates witnessing the will in 1131 there is not a single cleric. In the event it was a will that his nobles refused to carry out— instead bringing his brother Ramiro from the monastery to assume royal powers— an eventuality that Lourie suggests was Alphonso's hidden intent.
His final campaigns were against Mequinenza (1133) and Fraga (1134), where García Ramírez, the future king of Navarre, and a mere 500 other knights fought with him. It fell on 17 July. He was dead by September. Alfonso was a fierce, violent man, a soldier and nothing else, whose piety was wholly militant. He has a great role in the Spanish reconquest.