The 15th century saw a re-orientation in Iberian affairs. It began with the early stages of a Portuguese overseas empire, and closed with the discovery of America on behalf of the rulers of Castile and Aragon, just over nine months after the final surrender of Granada. Before this date however, both Castile and Aragon endured setbacks. Aragon was wracked by civil war, though its armies became increasingly similar to those of the rest of Europe. In castile private war and quixotic duels between nobles were a recurring problem, absorbing more enemy than the struggle against the moors. To the southern frontier the Duke of Medina Sidonia alone was able to field an army of 4000 cavalry from his Andalusian estate. A military review covering the Seville area in 1406 listed 142 royal knights, 964 other men-at-arms, 1276 crossbowmen and 3720 halberdiers plus 1904 soldiers from neighbouring villages. Such reviews were held three times a year.

The effective unification of castile and aragon under King Ferdinand and Queen Isabella meant that for the first time Granada faced a united foe. There had been a considerable increase in Christian aggession before this unification, but the final assault was more than a merely an oversized raid. It was a carefully planned assault designed to extinguish Muslim Iberia once and for all. Ferdinand was given command of all forces, and his strategy was simply to ‘roll up’ the kingdom of Granada from all sides, besieging outlying castles and towns before the final attack on the city of Granada. The bulk of Ferdinands army consisted of paid professionals. Only the great barons now fought as feudal vassals, bringing their own heavy cavalry lanzas, more numerous light cavalry jinetes and infantry units.

The vital artillery train was attached to the royal forces, which also included many hand-gunners. Other royal troops came from Santa Hermandad or Royal Brotherhood; this was a form of royal conscription established in 1476,paid through local funds but commanded by professionals. Local hermanded militia forces from southern Castile played an important part in the invasion, providing numerous light cavalry and crossbowmen, while other hermandadas came from various parts of Castile. So did the strange homicianos, condemned criminals offered pardon in exchange for military service. Similar Aragonese contingents used the same weapons and included troops from Sicily, while foreign volunteers also came from England, France, Burgundy, Germany and flanders. The campaign was long and bitter, with the Muslims putting up ferocious resistance. When the Christian camp outside Granada was burned down a permanent town called Sante Fe was erected in its place. Even this did not break the defenders will to resist. In the end the king of Granada negotiated a private surrender against the wishes of his people, secretly allowing Spanish troops into the Alhambra Palace on 2 January 1492.