The Battle of Isly was fought on August 14, 1844 between France and Morocco, near the Isly River. French forces under Marshal Thomas Robert Bugeaud routed a much larger, but poorly organized, Moroccan force, mainly fighters from the tribes of Beni Snassen, but also from the Beni Angad and Beni Oukil; under Muhammad, son of the Sultan of Morocco, Abd al-Rahman. Bugeaud, attempting to complete the French conquest of Algeria, instigated the battle without a declaration of war in order to force negotiations concerning Moroccan support for the Algerian resistance leader Abd el-Kader to conclude on terms favorable to the French who demanded the Sultan of Morocco to withdraw support for Abd el-Kader.

Thomas Robert Bugeaud, marquis de la Piconnerie, duc d'Isly was a Marshal of France and Governor-General of Algeria during the French colonization.