His uncle, caliph al-Mutawakkil (r. 847–861) had created a plan of succession that would allow his sons to inherit the caliphate after his death; he would be succeeded first by his eldest son, al-Muntasir, then by al-Mu'tazz and third by al-Mu'ayyad.Bosworth, "Mu'tazz," p. 793 In December 861 al-Mutawakkil was assassinated by a group of Turkic military officers, likely with the support of al-Muntasir. During al-Muntasir's short reign (r. 861–862), the Turks pressured him into removing al-Mu'tazz and al-Mu'ayyad from the succession. When al-Muntasir died, the Turkic officers gathered together and decided to install the dead caliph's cousin al-Musta'in on the throne.Bosworth, "Muntasir," p. 583
