Al-Amin

Al-Amin's reign was dominated by the Fourth Fitna, a civil war against his brother al-Mamun. The conflict began when al-Amin tried to remove al-Mamun from succession, leading to a devastating war that weakened the Abbasid Caliphate.

Al-Mamun's forces, led by Tahir ibn Husayn, besieged Baghdad in 812-813. The siege lasted over a year, causing widespread destruction and famine. Al-Amin was captured and executed in 813, ending his caliphate.

After the fall of Baghdad, al-Amin was captured by Tahir's forces. He was executed on al-Mamun's orders, marking the end of the civil war and the beginning of al-Mamun's sole rule.