Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Siege of Baghdad was a part of a civil war between Al-Amin and Al-Ma''mun for the Abbasid Caliphate of Baghdad. The siege lasted from August 812 until September 813. The siege is described in great detail by Muhammad ibn Jarir al-Tabari in his famous Tarikh al-Tabari (History of the Prophets and Kings).After the defeat of Caliph Al-Amins'' army at the Battle of Rayy and the death of his commander Ali ibn Isa ibn Mahan,the armies of Al-Amin were in retreat moving west from Iran to Iraq back to their base camp at Baghdad. Future Caliph Al-Ma''mun''s general Tahir ibn Husayn, the victor of Battle of Rayy decided to chase the retreating