Battle of Simancas: King Ramiro II of León defeats the Moorish army under Caliph Abd-al-Rahman III near the city of Simancas.

The Battle of Simancas was a military battle that started on 19 July 939 in the Iberian Peninsula between the troops of the King of León Ramiro II and Cordovan caliph Abd al-Rahman III near the walls of the city of Simancas.

Ramiro II, son of Ordoño II and Elvira Menendez, was a King of León from 931 until his death. Initially titular king only of a lesser part of the kingdom, he gained the crown of León after supplanting his brother Alfonso IV and cousin Alfonso Fróilaz in 931. The scant Anales castellanos primeros are a primary source for his reign.

The term Moor is an exonym used in European languages to designate the Muslim populations of North Africa and the Iberian Peninsula during the Middle Ages.

ʿAbd al-Raḥmān ibn Muḥammad ibn ʿAbd Allāh ibn Muḥammad ibn ʿAbd al-Raḥmān ibn al-Ḥakam al-Rabdī ibn Hishām ibn ʿAbd al-Raḥmān al-Dākhil, or simply ʿAbd al-Raḥmān III, was the Umayyad Emir of Córdoba from 912 to 929, at which point he founded the Caliphate of Córdoba, serving as its first caliph until his death. Abd al-Rahman won the laqab (sobriquet) al-Nāṣir li-Dīn Allāh in his early 20s when he supported the Maghrawa Berbers in North Africa against Fatimid expansion and later claimed the title of Caliph for himself. His half-century reign was known for its religious tolerance.

Simancas is a town and municipality of central Spain, located in the province of Valladolid, part of the autonomous community of Castile and León. It is situated approximately 10 km southwest of the provincial capital Valladolid, on the road to Zamora and the right bank of the river Pisuerga.