He joined the invasion of Jin Empire in 1211 with Jochi and Ögedei, capturing several cities and invading Shaanxi and Henan in 1213, also plundering Yanggu. Later Chagatai appeared at campaign against Khwarazmian Empire with his father and brothers, capturing Otrar in 1218, Samarkand in 1220, Urgench in March-April 1221. The Urgench campaign was noticeably harder because Chagatai and Jochi failed to co-operate. After this incident Ögedei was appointed commander of the besieging forces and Chagatai was given task of maintaining communication between Mongol forces with building bridges and restoring roads. He returned to his father's side during his siege of Talaqan. Chagatai was greatly affected when his son Mutukan was killed during the siege of Bamiyan in 1221.