Abu al-Faḍl Jaʽfar ibn Muḥammad al-Muʽtaṣim billāh;
(Arabic: جعفر بن محمد المعتصم بالله; March 822 – 11 December 861), better known by his regnal name al-Mutawakkil ʽalà Allāh (المتوكل على الله, “He who relies on God”) was an Abbasid caliph who reigned in Samarra from 847 until 861. He succeeded his brother al-Wathiq. His assassination on 11 December 861 by the Turkish guard with the support of his son, al-Muntasir, began the troubled period of civil strife known as “Anarchy at Samarra”.
He is known as the caliph who ended the Mihna.