Alfonso crossed the mountain range that defended the Almohad camp, sneaking through the Despeñaperros Pass, led by Martín Alhaja, a local shepherd who knew the area. The Christian coalition caught the Moorish army at camp by surprise, and Alhaja was granted the hereditary title Cabeza de Vaca for his assistance to Alfonso VIII. According to legend, the Caliph had his tent surrounded with a bodyguard of slave-warriors. Though it was once claimed that these men were chained together to prevent flight, it is considered more likely that this results from a mistranslation of the word "serried", meaning a densely packed formation. The Navarrese force led by their king Sancho VII broke through this bodyguard. The Caliph escaped, but the Moors were routed, leaving heavy casualties on the battlefield. The victorious Christians seized several prizes of war; Muhammad al-Nasir's tent and standard were delivered to Pope Innocent III. Christian losses were far fewer, only about 2,000 men. The losses were particularly heavy among the Orders. Those killed included Pedro Gómez de Acevedo, Alvaro Fernández de Valladares, Pedro Arias and Gomes Ramires. Ruy Díaz was so grievously wounded that he had to resign his command. Muhammad al-Nasir died in Marrakech shortly afterwards.
Aftermath
The crushing defeat of the Almohads significantly hastened their decline both in the Iberian Peninsula and in the Maghreb a decade later. That gave further impulse to the Christian Reconquest and sharply reduced the already declining power of the Moors in Iberia. Shortly after the battle, the Castilians took Baeza and then Úbeda, major fortified cities near the battlefield and gateways to invade Andalusia. According to a letter from Alfonso VIII of Castile to Pope Innocent III, Baeza was evacuated and its people moved to Úbeda; Alfonso laid siege, killing 60,000 Muslims and enslaving many more. According to the Latin Chronicle of Kings of Castile the number given is almost 100,000 Saracens, including children and women, who were captured. Thereafter, Alfonso VIII's grandson Ferdinand III of Castile took Cordova in 1236, Jaén in 1246, and Seville in 1248; then he took Arcos, Medina-Sidonia, Jerez, and Cádiz. In 1252, Ferdinand was preparing his fleet and army for invasion of the Almohad lands in Africa. But he died in Seville on 30 May 1252, during an outbreak of plague in southern Hispania. Only Ferdinand's death prevented the Castilians from taking the war to the Almohad on the Mediterranean coast, James I of Aragon conquered the Balearic Islands and Valencia. By 1252 the Almohad empire was almost finished, at the mercy of another emerging African power. In 1269 a new association of African tribes, the Marinids, took control of the Maghreb, and most of the former Almohad empire was under their rule. Later, the Marinids tried to recover the former Almohad territories in Iberia, but they were definitively defeated by Alfonso XI of Castile and Afonso IV of Portugal in the Battle of Río Salado, the last major military encounter between large Christian and Muslim armies in Hispania.
's 1972 alternate history/science fiction novel Tunnel Through the Deeps depicts a history where the Moors won at Las Navas de Tolosa and retained part of Spain into the 20th century.
