The Umayyad Caliph at last recognised the gravity of the situation, and sent all the forces he could muster to oppose Kahtaba. But the Hashimite troops carried all before them. They defeated a large Syrian army near Isfahan, and captured the important stronghold of Nahavend, A.H. 132 (749). Then Kahtaba started for Kufa, making a slight detour to avoid Ibn Hobayra, who was encamped at Jalula. On reaching the Euphrates, Ibn Hobayra came up with him, and a battle ensued at nightfall near Kerbela. Kahtaba perished,178 but his son Hasan continuing the fray defeated Ibn Hobayra, and drove him back on Wasit. Meanwhile the Yemenites revolted in Kufa, and on the arrival of the victorious Hashimite forces179 delivered up the town to them. On the entry of Hasan ibn Kahtaba into Kufa the head of the `Abbasid house, Abu-l-`Abbas, emerged from his hiding-place, and the town for the time became the seat of the `Abbasids. Abu Salama was provisionally recognised as the Vezir of the house of Mohammed. Meanwhile the fate of the Umayyads had been decided by the battle of the Zab in Mesopotamia, A.H. 132 (750), where Merwan himself, surrounded by his greatest generals, encountered the Hashimites under `Abdullah, Abu-l-`Abbas’s uncle. Merwan suffered a crushing defeat, and fled, hotly pursued, to Egypt, where he was finally captured and slain.

At the beginning of this year Abu-l-`Abbas, called Es-Saffah, or the “Shedder of Blood,” was proclaimed Caliph in the great mosque of Kufa. The new Caliph’s first measure was to sweep the entire Umayyad race from the face of the earth. The traditions which have come down to us of his butcheries pass all belief.180 Syria was soon reduced, and Ibn Hobayra surrendered his last retreat, Wasit. But troubles continued throughout his reign. Abu Muslim’s attempts to put all the Umayyad faction to the sword led to a serious rising in Khorasan. The partisans of the fallen dynasty, in Bokhara, Soghdiana, and Farghana, aided by the emperor of China, took the field in force, but were soon dispersed with great slaughter by Ziyad, governor of Samarkand. “It is plain,” says VambÉry,181 “from the historical sources before us that the original Iranian population of the land, namely, the Tajiks, fought under the banner of Nasr, and long remained true to the cause of the Ommayades.”

“The resistance which Nasr ibn Sayyar offered not only to the superior force, but also to the allurements of Ebu Muslim, deserves our respect.”

“On the other hand, the adroitness of Ebu Muslim deserves our admiration, who in an astonishingly short space of time gained over to his side all the Turks of Transoxiana, and attached them to himself to such a degree that the myths which even now live in the mouths of the Ozbegs and Turcomans compare him to the Caliph Ali for valour and wondrous works. At all events the influential individuality of Ebu Muslim first made the warlike supremacy of the Turks, although only mediately, felt in Western Asia.”

About the year A.H. 134 (751) the new Caliph’s brother paid an official visit to Merv, in order to report on the state of the Eastern provinces. So much alarmed was he at the influence and independence of Abu Muslim that on his return to Kufa he recommended his brother to rid himself of the man to whom he owed his throne. In the following year Ziyad, the governor of Samarkand, probably at the instigation of the Caliph, rose against Abu Muslim; but the movement was quickly crushed, and Ziyad was deposed and put to death.

In the following year, A.H. 136 (753), while Abu Muslim and Abu Ja`far were returning from a pilgrimage to Mekka, the Caliph es-Saffah died in Anbar. Abu Ja`far, who is well known in history as El-Mansur, had been designated by his brother to succeed him,182 but he had a rival in the person of his uncle `Abdullah, who was at the head of a considerable army, including a contingent of 17,000 men of Khorasan. Abu Muslim, compelled to choose between the pretenders, declared for Abu Ja`far, whereupon `Abdullah caused a massacre of the whole of his Khorasan contingent,183 in the knowledge that they would refuse to draw the sword against the governor of their province. But the precaution was of no avail, for shortly afterwards his Syrian army was utterly defeated near Nisibis by a Persian force under Abu Muslim, and `Abdullah was compelled to abandon his claim. Hardly was this danger averted when the Caliph el-Mansur again allowed his jealousy of Abu Muslim to get the better of him. Abu Muslim was warned of his ill-will, so resolved an immediate return to Khorasan. In order to prevent this the Caliph appointed him to the governorship of Syria and Egypt, and invited him to an audience in Mada´in. The correspondence184 which followed between the Caliph and his too powerful lieutenant gives us a graphic picture of the times, and also possesses some historical importance. Abu Muslim was too wary to accept the Caliph’s invitation. “A certain king of the Sasanides,” he replied, “once said: ‘There is no more dangerous time for a Vezir than when complete tranquillity reigns in the kingdom.’ ... I therefore deem it expedient to avoid the proximity of the Commander of the Faithful, without, however, ceasing on this account to be his faithful subject. Should the Commander of the Faithful allow me to do so I will be the most humble of his servants, but if he gives vent to his passions I shall be compelled for my own safety to recall my allegiance.”

To this the Caliph replied: “I have grasped the meaning of thy letter; but thy position is different from that of the bad Vezirs of the Sasanide kings, ... a humble and faithful servant like thyself has nothing to fear during a state of peace. Although the conditions hinted at towards the close of thy letter do not bespeak an entire submission, thou wilt doubtless return with the bearer of this letter. I pray God that He may give thee strength to withstand the enticements of Satan, who hopes to frustrate thy good intentions, and opens for thee the gate which leads to destruction.”

Abu Muslim rejoined in the following remarkable letter: “I had a guide closely connected with the house of the Prophet whose business it was to instruct me in the teachings and duties prescribed by God. From him I had hoped to learn the sciences, but he led me into ignorance and error by means of the Koran itself, which, from love of worldly things, he misinterpreted. He ordered me, in God’s name, to draw the sword, to banish feelings of pity from my heart, to accept no excuses from my enemies, and to pardon no offence. I did everything to pave his way to dominion. Nothing now remains for me but to entreat God to pardon me for the sins I have committed.” Having despatched this letter, Abu Muslim set out for Khorasan, but in the meanwhile El-Mansur wrote privately to Abu Da´ud Khalid, whom Abu Muslim had left as his lieutenant in Khorasan, appointing him to the governorship. He further pointed out that the army of Khorasan had obeyed Abu Muslim because he had been fighting for the `Abbasids; that he was now in open revolt, and ought to be put to death at the first opportunity. Abu Da´ud communicated this letter to the army and chiefs of Khorasan, who at once recognised him as governor. He then sent news of this momentous occurrence to Abu Muslim, who, seeing that he could no longer count on the attachment of the Khorasanis, and deceived by the false assurances of his former friends, consented to wait upon the Caliph at Mada´in. On arriving there he was basely murdered at his master’s instigation by five hired assassins, A.H. 137 (754).

Abu Muslim was barely thirty-five years of age when he met his fall. It was certainly deserved, for, according to computations of Arabian historians, he was responsible for the slaughter of no less than 600,000 human beings. But though the monster richly merited punishment, his master, on whom he had bestowed the Empire of the East, should have been the last to inflict it; and the treachery with which Abu Muslim’s fate was compassed is an additional stain on El-Mansur’s memory.