Battle of Las Navas de Tolosa.

Muslim victories over the Knights of Calatrava in September, 1211, spurred Alfonso VIII of Castile to send Archbishop of Toledo Ximénes de Rada to Rome to ask Pope Innocent III to endorse a Spanish crusade. Ximénes preached the crusade in Italy, Germany, and France, and 70,000 northerners joined Alfonso’s 60,000 Spanish troops at Toledo in spring, 1212. Diego López de Haro led the northern vanguard out of Toledo on June 20. King Pedro II and his Aragonese followed, and Alfonso’s Castilian troops and members of the military orders brought up the rear. They took Malagón (June 24) and Calatrava (July 1) before most of the northern troops returned northward. Heat, disease, and disgust with humane treatment of the Muslims (no plunder) by the Spanish drove them off. This loss was compensated in part by the arrival of Sancho VII of Navarre and his troops. After taking several more strongholds, the force reached Las Navas de Tolosa on July 13, where they were blocked by the army of Muḥammad al-Nāṣir, the emir of Morocco. The weakened López de Haro held the Christian center, with Pedro on the left and Sancho on the right. Alfonso held his large force in reserve. On July 16, Pedro and Sancho acted as pincers, while Alfonso crushed the Muslim center. Muḥammad al-Nāṣir fled, leaving untold thousands of Muslim dead. His tent and standard were sent to Pope Innocent.