Battle of Sagrajas (az-Zallaqa)

After the collapse of the caliphate of Córdoba, al-Andalus had split into taifa kingdoms that paid tribute to the Christian kings of the north. When Alfonso VI took Toledo in May 1085 and then laid siege to Zaragoza, al-Mu'tamid of Seville, al-Mutawakkil of Badajoz and Abdallah of Granada appealed to Yusuf ibn Tashfin; al-Mu'tamid is said to have remarked that it was better to pasture camels than to be a swineherd. Yusuf demanded Algeciras as a base, occupied it in July 1086, brought his army across the strait and joined the taifa forces at Seville, while Alfonso lifted the siege of Zaragoza and marched south.

The armies met at a place north of Badajoz which the Arabic sources call az-Zallaqa, "slippery ground", and the Christian sources Sagrajas. According to the Muslim accounts, the day of battle had been agreed for a Monday, but the Castilians attacked at dawn on Friday, 23 October. The Andalusian contingents gave way while al-Mu'tamid held out, until the main Almoravid forces under Sir ibn Abi Bakr and Yusuf's guard of black African soldiers fell upon the Castilians and routed them; Alfonso escaped with a wound in the leg that left him lame for life. The chroniclers' figures for the size of the armies vary widely.

Yusuf did not pursue the beaten army: after a short stay at Seville he returned to Africa, probably because of the death of his son and heir. Castile kept Toledo and soon resumed its pressure on the taifas, but the balance had changed. Yusuf came back in 1088 to besiege Aledo in vain, and in 1090, supported by the Maliki jurists of al-Andalus, he turned against the taifa kings themselves: Granada fell in 1090, Seville in 1091 and Badajoz in 1094, and al-Andalus became part of an empire ruled from Marrakesh.