The main incident during the Imamat of Imam Reza (AS) was his appointment as Ma’mun’s Crown Prince. To fulfill his plot, Ma’mun, the Caliph, brought the Imam from Medina to his capital in Merv and threatened the Imam to accept his proposal to be his Crown Prince. The Imam’s nomination as the Crown Prince was a very unusual proposal, as the Imam was about 22 years older than Ma’mun. Everyone was expecting a younger person than the Caliph for the Crown Prince, as he would inherit the Caliphate after the Caliph. Ma’mun, with his well-planned and secret conspiracy, intended to eliminate Shi’ism entirely by showing the Imam as a worldly and materialistic individual, disgracing him in the eyes of Muslims. However, the Imam, with his wise decisions and behaviors, made Ma’mun’s conspiracy ineffective. Ma’mun realized that his plots against the Imam had failed, so he poisoned the Imam himself, martyring him after the Imam had been the Crown Prince for only about one-and-a-half years.