Sykes' History of Persia Vol 2 (pdf) - Heritage Institute

XLIX THE EARLY ABBASID PERIOD 63
and it
may have been due to his cruelty that a rebellion
broke out in Syria and Mesopotamia, where large armies
still
supported the Omayyad cause. Basra, too, defied
the Khorasan troops of the Hashimite general, and had
there been a master-mind to give unity to these efforts
it
might have gone hard with the house of Abbas but
;
none such was to be found. Ibn Hobayra clung to
Wasit at a time when his army might have saved the
Omayyad cause in Syria, and he was induced to capitulate.
The Khorasan veterans at length captured Basra, and
although in Khorasan and other outlying provinces risings
occurred, the Abbasid dynasty was before long firmly
established.
The treachery and ingratitude of Abul Abbas were
displayed in the assassination of Abu Salma, who was
waylaid when returning from a feast given in his honour
by the Caliph. Shortly afterwards Abul Abbas himself
died of small-pox.
The five years of his reign had been
marked by massacres, treachery, perjury, and ingratitude
on a scale unprecedented in the annals of Islam.
Abu Jafary Mansur , A.H. 136-158 (754-775). Abu
Jafar, who succeeded to the Caliphate and assumed the
title of Mansur or Victorious, was faced with a serious
rebellion headed by
his uncle Abdulla, the Conqueror of
Merwan. Abu Muslim was sent to oppose him, and the
Pretender in desperation butchered 17,000 Khorasan
troops whom he knew he could not trust. Abu Muslim
in the end succeeded, and Abdulla was taken prisoner
and placed in custody at Basra.
The Execution of Abu Muslim, A.H. 137 (754). Just
as Abul Abbas had planned the assassination of Abu
Salma, so the ungrateful Mansur determined to kill the
too-powerful Abu Muslim. The latter, suspecting
treachery, asked one of his friends how he thought he
stood with the Caliph. The friend replied in a parable.
"
A lion had his foot pierced by a thorn, so that it was
unable to move ;
and a simple-minded, well-meaning
man, seeing its weakness and hearing its moaning, took
pity on it, approached it,
and drew forth the thorn from
its foot.
Thereupon the lion slew the man c
;
for/ it said,