The Eleventh Imam: Al-Hasan Ibn Ali Al-Askari (Peace be on him)
Agnomen: Abu Muhammad.
Father's name: `Ali al-Hadi (an-Naqi).
Mother's name: Hadithah (or Susan).
Birth: In Medina, on Friday, 8th Rabi’u'th-thani 232 AH.
Death: Died at the age of 28, in Samarra', on Friday, 8th
Rabi’ul-awwal 260 AH; poisoned by al-Mu'tamid,
the Abbasid ruler; buried in Samarra' (Iraq).
Imam Hasan ibn Ali al-Askari, the son of the Tenth Imam, was born in 232/845 and according to some Shiite sources was poisoned and killed in 260/872 through the instigation of the Abbasid caliph al-Mu'tamid. The Eleventh Imam gained the Imamate, after the death of his noble father, through Divine Command and through the decree of the previous Imams. During the seven years of his Imamate, due to untold restrictions placed upon him by the caliphate, he lived in hiding and dissimulation (taqiyyah). He did not have any social contact with even the common people among the Shi`ite population. Only the elite of the Shi'ah were able to see him. Even so, he spent most of his time in prison.
Here it should be remembered that during their lifetime the Imams trained many hundreds of scholars of religion and hadith, and it is these scholars who have transmitted to us information about the Imams.
al-Imam al-Hasan al-`Askari, peace be on him, said:
* Generosity has a limit, which when crossed becomes extravagance; caution has a limit which when crossed becomes cowardice; thriftiness has a limit, which when crossed becomes miserliness; courage has a limit, which when crossed becomes fool-hardiness. Let this moral lesson suffice: refrain from doing anything which you would disapprove of if done by someone else.
A Brief History of The Fourteen Infallibles
Here For Full Length