Ma’mun...

Ma’mun, in turn, dispatched four thousand troops under the commandment of Tahir b. Husayn to fight back and the two armies met in battle near Rey. Being proud of the great number of his troops and having failed to act with foresightedness, the commander of Amin’s army was defeated and killed by Ma’mun’s troops. After this victory, Ma’mun deposed his brother Amin and dispatched Tahir b. al-Husayn to Baghdad along with Harthamat b. A‘yan.

After fighting for a while and besiege of Baghdad, the people of Baghdad became exhausted and withdrew from Amin. Also, Tahir made dignitaries inclined towards Ma’mun by promising gold and silver to them, and…