Following the flight of Jalāl al-Dīn Khwarazmshāh from the Mongols to the Jazira and Lesser Armenia and his subsequent death, the Khwarazmian army—numbering approximately twelve thousand soldiers—was left without a commander. This army soon attracted the attention of neighboring rulers. The present study examines the role of the remnants of the Khwarazmian army in the internal developments of the Ayyubid realm and in the struggle against the Crusaders. Using reliable historical sources, this research investigates the relations between the Khwarazmian forces and the Ayyubids, and explores the role of the Khwarazmians in developments related to the Crusades. The findings indicate that the Khwarazmian army became a sought-after military force among Ayyubid emirs. The Ayyubids sought both to restrain this army and to employ it in confronting their own enemies. Although the insubordination of the Khwarazmians caused divisions among regional rulers and compelled Muslim rulers to expend part of their resources to suppress their disturbances, a change in the conduct of this army gradually enabled their participation in the Crusades. Their most significant role was the defeat of the Crusaders and the recapture of Jerusalem in 1244 CE.