During the siege of Kut, Mirza Mahdi travelled to Kadhimiya, with his uncle Mirza Taqi, who feared that Samarra could end up like Kut, and that way many from the religious sphere would die. They remained in Kadhimiya for approximately a year and a half, living a life of dire poverty, until they returned to Karbala, where Mirza Taqi, was preparing to lead the Iraqi revolt against the British administration. He remained in Karbala, and played an active supporting role with his uncle in the Iraqi revolt, until his uncle was poisoned in 1920.