By: Mir M.Hosseini
The Battle of Rhagae was fought on May, 1, 811 between the two sons of Harunolrashid, Al-Amin and Al-Mamun.
In 802 Harunolrashid,, ordered that Amin succeed him, and Mamun serve as governor of Khorasan and become caliph after Amin. Mamun was the older of the two brothers and his mother was a Persian woman. After Harunolrashid 's death in 809, the relationship between the two brothers deteriorated. In response to Mamun's moves toward independence, Amin declared his own son Musa to be his heir. This violation of Harunolrashid's testament led to a civil war in which Iranians supported Mamun and defeated Amin's armies and laid siege to Baghdad.
First, Amin sent an army out to destroy his brother, which left Baghdad on March, 14, 811. Mamun's army was led by Taher ibn Hossein, a Persian nobleman and the founder of the Taherian Dynasty. Near Rhagae, the battle started with a lightning attack of 700 Kharazmian archers that swiftly destructed Amin’s army structure and killed Ali, the army commander. The Caliph army was dispersed. Taher recognized his opportunity and took his almost-undamaged army on to Baghdad. After a lengthy siege Baghdad fell and Amin was killed.
In 813 Mamun was recognized as Abbasi caliph throughout the empire, yet he would not arrive in Baghdad until 819 due to the destruction and continued disturbances in the city.