Hasan al-Askari

Abu Muhammad al-Hasan b. Ali, known as al-Askari, is regarded in the Twelver Shia tradition as the eleventh of the Twelve Imams, the line of leaders Twelvers hold to be the rightful spiritual successors of the Prophet Muhammad. (Other Muslim communities — Sunni, Ismaili, Zaydi and others — do not share this enumeration; the Imamate is a Twelver doctrinal position, not an agreed historical fact.)

He was born in Medina, with the date genuinely disputed in the sources: common Shia tradition gives around 232 AH (846 CE), while much of the academic and Encyclopaedia-of-Islam tradition leads with 230 AH (844 CE), and reported dates range across roughly 844-847 CE (230-232 AH). While still a small child he was brought with his father, the tenth Imam Ali al-Hadi, to Samarra, the Abbasid capital and military camp north of Baghdad. His epithet al-Askari ("the military one") reflects this: the family was made to live in the garrison quarter (al-askar) under close surveillance. Reports describe periods of detention, including under the caliphs al-Mu'tazz and al-Mu'tamid.

He died at Samarra in 260 AH (874 CE), aged about 28, and was buried beside his father in the home that later became the al-Askari shrine, a major Shia pilgrimage site. Shia tradition commonly holds that he was poisoned at the instigation of the caliph al-Mu'tamid; this is a traditional claim, not an established fact.

His death caused a crisis of succession. Early sources record that his followers split into many groups (counts range up to about twenty). The party that became the Twelvers held that he had left a young son, Muhammad, who entered "occultation" (ghayba, a hidden state) as the awaited Mahdi — a belief other early Shia disputed, some denying he had left a son at all.