, which he had already
purposely entrusted to his brother, Abu Ja'far.

Abu'l-Abbas died on the 13th of Dhu'l-hijja 136 (5th June 754). He seems
to have been a man of limited capacity, and had very little share in the
achievements accomplished in his name. He initiated practically nothing
without the consent of Abu Jahm, who was thus the real ruler. In the few
cases where he had to decide, he acted under the influence of his
brother Abu Ja'far.

2. _Reign of Mansur._--Abu'l-Abbas had designated as his successors
first Abu Ja'far, surnamed al-Mansur (the victorious), and after him his
cousin 'Isa b. Musa. Abu Ja'far was, according to the historians, older
than Abu'l-Abbas, but while the mother of the latter belonged to the
powerful Yemenite tribe of al-Harith b. Ka'b, the mother of Abu Ja'far
was a Berber slave-girl. But he was a son of Mahommed b. Ali, and was
therefore preferred by Abu Moslim to his uncles and cousins.
Abu'l-Abbas, however, had promised the succession to his uncle Abdallah
b. Ali, when he marched against Merwan. When the news of the death of
Abu'l-Abbas reached Abdallah, who at the head of a numerous army was on
the point of renewing the Byzantine war, he came to Harran, furious at
his exclusion, and proclaimed himself caliph. Abu Moslim marched against
him, and the two armies met at Nisibis, where, after a number of
skirmishes, a decisive engagement took place (28th November 754).
Abdallah was defeated and escaped to Basra, where he found a refuge with
his brother Suleiman. A year later he asked for pardon, and took the
oath of allegiance to Mansur. The caliph spared his life for a time, but
he did not forget. In 764 Abdallah met his death by the collapse of his
house, which had been deliberately undermined.

The first care of Mansur was now to get rid of the powerful Abu Moslim,
who had thus by another brilliant service strengthened his great
reputation. On pretence of conferring with him on important business of
state, Mansur induced him, in spite of the warnings of his best general,
Abu Nasr, to come to Madain (Ctesiphon), and in the most perfidious
manner caused him to be murdered by his guards. Thus miserably perished
the real founder of the Abbasid dynasty, the _Sahib addaula_, as he is
commonly called, the _Amin_ (trustee) of the House of the Prophet. A
witty man, being asked his opinion about Abu Ja'far (Mansur) and Abu
Moslim, said, alluding to the Koran 21, verse 22, "if there were two
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