At the Battle of Sagrajas, the army of Yusuf ibn Tashfin defeats the forces of Castilian King Alfonso VI.
The Battle of Sagrajas (23 October 1086), also called Zalaca or Zallaqa (Arabic: معركة الزلاقة, romanized: Maʿrakat az-Zallāqa), was a battle between the Almoravid army led by their King Yusuf ibn Tashfin and an army led by the Castilian King Alfonso VI. The battleground was later called az-Zallaqah (in English "slippery ground") because of the poor footing caused by the tremendous amount of blood shed that day, which gave rise to its name in Arabic.