Mongol campaign against the Nizaris

Battle context

The Mongol campaign against the Nizaris, ordered by Great Khan Möngke and placed under the command of his brother Hülegü, was conceived as part of a broader westward extension of Mongol power following the invasion of the Khwarazmian Empire and a sequence of Nizari–Mongol conflicts. The campaign targeted the Nizari state centered on Alamut and was paired with operations against the Abbasid Caliphate, with the combined objective of establishing a new Mongol khanate in the region — what would become the Ilkhanate. In that sense the campaign was not an isolated punitive expedition but a foundational element of Mongol imperial reorganization in western Asia. The scale of the effort is indicated by the commitment of fifty thousand troops under a constellation of senior commanders including Kitbuqa, Guo Kan, and Abaqa alongside Hülegü, while recorded Mongol casualties of one hundred thousand — double the stated force — point to the severity of the resistance encountered across the campaign's duration. The Nizari leadership, including Rukn al-Din Khurshah and the scholar Nasir al-Din al-Tusi, were drawn into the conflict as the Mongols pressed against the mountain fortresses of the Alamut period, ultimately dismantling one of the most distinctive political and military structures of the medieval Islamic world.