Battle of Rayy

Part of the Fourth Fitna

Date	May 1, 811
Location	Rayy, Iran
Result	Decisive victory for Al-Ma'mun

Belligerents

Al-Amin's forces

Al-Ma'mun's forces

Commanders and leaders

Ali ibn Isa ibn Mahan †

Tahir ibn Husayn

Strength

Around 50,000

>10,000

Casualties and losses

High

Low

This Battle of Rayy (one among many) was fought on May 1, 811 CE as part of an Abbasid civil war (the "Fourth Fitna") between the two half-brothers, al-Amin and al-Ma'mun.

Caliph Harun al-Rashid (the father of the two brothers) had foreseen that upon his death there would be a struggle between the two for succession to the Caliphate (the first born succession concept used in Christian monarchies was not prevalent in Islam). Thus he decreed that al-Amin would rule the Abbasid Caliphate until his death, while al-Ma'mun acted as viceroy of Khurasan province in Eastern Iran. Then al-Ma'mun or one of his sons would succeed al-Amin as caliph, and in turn be succeeded by someone chosen by al-Amin.

Naturally such a scheme, well-intentioned as it was, was doomed to fail. Both brothers were influenced by their viziers, Fadl ibn al-Rabi and Fadl ibn Sahl respectively, into attempting to claim power. Ultimately al-Amin declared that his sons would reign as Caliphs after he had died, even going as far as to seize the documents binding the brothers to the agreement from the sacred city of Mecca. Al-Ma'mun was much angered by this and prepared for war, his vizier sending a force to defend the key frontier stronghold of Rayy, between the Zagros and Elburz mountain ranges. Meanwhile, al-Amin sent an army out to destroy his brother, which left Baghdad on March 14, 811 CE.

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