Mongol campaign against the Nizaris
The Mongol campaign against the Nizaris of the Alamut period (the Nizari Ismaili state) began in 1253 after the Mongol invasion of the Khwarazmian Empire and a series of Nizari–Mongol conflicts. The campaign was ordered by the Great Khan Möngke and was led by his brother, Hülegü.
Source: Wikipedia — Mongol campaign against the Nizaris (CC BY-SA 4.0)