Al-Mutawakkil

Ja'far ibn Muhammad became the tenth Abbasid caliph in 847, taking the throne after his brother al-Wathiq. Deeply religious, he reversed the Mu'tazila doctrine that had dominated the court, ended the Mihna - a sustained persecution of scholars - and freed the imprisoned jurist Ahmad ibn Hanbal. Under his rule the empire reached its maximum territorial extent, though his governance toward non-Muslims was harsh. On 11 December 861, members of the Turkic guard assassinated him with the backing of his own son, al-Muntasir. The killing opened what became known as the Anarchy at Samarra, a spiral of civil war that would unravel the caliphate's grip on power.