[2] In 849, al-Mutawakkil arranged for his succession, by appointing three of his sons as heirs and assigning them the governance and proceeds of the Empire's provinces: the eldest, al-Muntasir, was named first heir, and received governorship of Egypt, the Jazira, and the proceeds of the rents in the capital, Samarra; al-Mu'tazz was charged with supervising the domains of the governor in the Khorasan; and al-Mu'ayyad was placed in charge of Syria.
The Turkic regiments then prevailed on al-Muntasir to remove his brothers from the succession, fearing revenge for the murder of their father.
When al-Muntasir died of unknown causes, the Turkic officers gathered together and decided to install the dead caliph's cousin al-Musta'in (al-Mutawakkil's Nephew) on the throne.
[4] The new caliph was almost immediately faced with a large riot in Samarra in support of the disenfranchised al-Mu'tazz; the rioters were put down by the military but casualties on both sides were heavy.
He was smothered in a downy robe (or, as others say, frozen in a bed of ice); and the body was then exposed before the Court, as if, being without mark of violence, he had died a natural death, (a transparent subterfuge).