For the next century, Granada hung onto its lands on the southeastern edge of Spain and made tribute payments with gold that had been brought across the Sahara by merchants on camelback. The Nasrid people there worked in an uneasy alliance with Castile, fighting alongside in Spain and against the Muslim Kingdom of Fez and its ally Aragon in the early 1300s. Gradually, however, the peace began to crack. In 1325, King Alfonso XI of Castile declared war on Granada and set out to conquer while giving an invitation to other Christian kings to join his crusade. While his call went largely unanswered in the first campaign, the second was answered by Portugal and a contingent of Scottish knights bearing Robert the Bruce’s heart in 1330. They attacked and took Teba, a key castle Granada, which prompted King Yusuf I to call for aid from the Marinid sultan of Morocco, Abu al-Hasan 'Ali.
Abu Hasan sent a small force in 1333, conquering Gibraltar and securing a foothold for his larger army to land. In late summer of 1340, Abu Hasan’s fleet wiped out the Castilian ships, outnumbered three-to-one, and then he move moved his vast new army onto the Spanish mainland. King Alfonso hurried to put together an army to face him and, most importantly, rebuild his fleet. In October, Alfonso’s new fast-built fleet of 27 ships joined 15 hired from Genoa and secured the Strait for Castile. Cut off from his supply-lines, Abu Hasan moved onto a siege of the castle at Tarifa. In mid-October, Alfonso marched with his army and joined up with his father-in-law, the King of Portugal, to create a force some 20,000 strong. Abu Hasan moved back from his siege and onto a defensive hill with the Granadan army of Yusuf on a hill nearby.
Upon the night of his arrival, Alfonso sent a force of 1,000 cavalry and 4,000 infantry to reinforce Tarifa. They met with Abu Hasan’s light cavalry on patrol, who pinned them with skirmishes until finally driving them back to Alfonso’s main army. The cavalry officer reported proudly to Abu Hasan that no Christian had managed to enter the city. This would become instrumental in keeping the Tarifa garrison unable to aid the Castilian forces as they faced the sultan while the Portuguese and Leonese attacked Yusuf the next morning across the Rio Salado.
Initially, the battle seemed to go to Castilians, whose right flank took a bridge and center crossed to smash through the Moroccan’s line and be caught fighting with the militia as it raided the Muslim camp. In the chaos, Abu Hasan ordered an all-out attack, which came at the same time Alfonso found himself isolated from the main army. Though he tried to escape, both Alfonso and the Archbishop of Toledo would be cut down. The Castilian rearguard arrived too late; the drop in morale gave Abu Hasan the chance to push and break the Christian army. Yusuf’s forces were overrun, but Abu Hasan managed to turn about his army and defeat the remaining Christians while driving the attackers from their attempt to take his camp before resuming a successful siege against Tarifa.
The tide of power would change to give Muslims a stronger grip on southern Spain as the war with Castile ended in a stern treaty. Granada became a Moroccan vassal, and Abu Hasan would work to increase his navy to firmly establish control of the Strait of Gibraltar, having learned his lesson about maintaining supply lines. The coming of the Black Death suspended ideas of further warfare, and afterward the Ottomans would absorb the Moroccan wealth under Suleiman the Magnificent with aid from the Franco-Ottoman alliance that promised France conquest of the small kingdoms in northern Spain.
While the Mediterranean saw more concrete Islamic dominance, an Italian with an Anglicanized name of Christopher Columbus approached the English court of Henry VII to back an expedition westward, and his resulting discoveries would be the focus of much of the later Henry VIII’s rule, establishing an English Empire across the New World.
In reality, the Castilian contingent reached Tarifa and reinforced the garrison despite the cavalry commander’s claim. In the next day’s battle, the garrison was able to attack the Moroccan camp also, then joining up with the Castilian forces to surround Abu Hasan’s army. The Muslim army broke and was pursued relentlessly with many slain and the riches of the camp seized. It would be the last Muslim invasion of the Iberian Peninsula. The completion of the Reconquista in 1491 after the marriage of Ferdinand II of Aragon and Isabella I of Aragon would unite Spain, which would dispatch the expedition by Cristóbal Colón in 1492.