Abu al-Faḍl Jaʽfar ibn Muḥammad al-Muʽtaṣim billāh, better known by his regnal name Al-Mutawakkil ʽalà Allāh was the tenth Abbasid caliph, under whose reign the Abbasid Empire reached its territorial height. He succeeded his brother al-Wathiq. Deeply religious, he is known as the caliph who ended the Mihna (persecution against many Islamic scholars), released Ahmad ibn Hanbal, and discarded the Muʿtazila, but he has been also subject of criticism for being a tough ruler towards the non-Muslim citizens. His assassination on 11 December 861 by the Turkic guard with the support of his son, al-Muntasir, began the troubled period of civil strife known as "Anarchy at Samarra".