His earliest years were passed in the monastery of Siresa, learning to read and write and to practice the military arts under the tutelage of Lope Garcés the Pilgrim, who was repaid for his services by his former charge with the county of Pedrola when Alfonso came to the throne.

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, and Bailo.

A series of deaths put Alfonso directly in line for the throne.
 His brother's children, Isabella and Peter (who married María Rodríguez, daughter of El Cid), died in 1103 and 1104 respectively.
His earliest years were passed in the monastery of Siresa, learning to read and write and to practice the military arts under the tutelage of Lope Garcés the Pilgrim, who was repaid for his services by his former charge with the county of Pedrola when Alfonso came to the throne.
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, and Bailo.
A series of deaths put Alfonso directly in line for the throne.  His brother's children, Isabella and Peter (who married María Rodríguez, daughter of El Cid), died in 1103 and 1104 respectively.
Alfonso the Battler