ahommed was defeated and slain. His head
was cut off and sent to Mansur. When on the point of death, Mahommed
gave the famous sword of the Prophet called Dhu'l-Fiqar to a merchant to
whom he owed 400 dinars. It came later into the possession of Harun
al-Rashid. In the meanwhile Ibrahim had not only gained possession of
Basra, Ahwaz and Fars, but had even occupied Wasit. The empire of the
Abbasids was in great jeopardy. For fifty days Mansur stayed in his
room, neither changing his clothes nor allowing himself a moment's
repose. The greater part of his troops were in Rei with his son
al-Mahdi, who had conquered Tabaristan, in Africa, with Mahommed b.
Ash'ath, and in Arabia with 'Isa b. Musa. Had Ibrahim marched at once
against Kufa he might have crushed Mansur, but he let slip the
opportunity. A terrible conflict took place at Ba-Khamra, 48 m. from
Kufa. Homaid b. Qahtaba, the commander of Mansur's army, was defeated,
only a small division under 'Isa b. Musa holding its ground. At that
moment Salm, the son of the famous Qotaiba b. Moslim, came to the rescue
by attacking the rear of Ibrahim. Homaid rallied his troops, and Ibrahim
was overpowered. At last he fell, pierced by an arrow, and, in spite of
the desperate efforts of his followers, his body remained in the hands
of the enemy. His head was cut off and brought to Mansur.

Mansur could now give his mind to the founding of the new capital. When
the tumult of the Rawendis took place he saw clearly that his personal
safety was not assured in Hashimiya,[29] where a riot of the populace
could be very dangerous, and his troops were continually exposed to the
perverting influence of the fickle and disloyal citizens of Kufa. He had
just made choice of the admirable site of the old market-town of Bagdad
when the tidings came of the rising of Mahommed in Medina. In those days
he saw that he had been very imprudent to denude himself of troops, and
decided to keep henceforth always with him a body of 30,000 soldiers. So
Bagdad, or properly "the round city" of Mansur, on the western bank of
the Tigris, was built as the capital. Strictly it was a huge citadel, in
the centre of which was the palace of the caliph and the great mosque.
But around this nucleus there soon grew up the great metropolis which
was to be the centre of the civilized world as long as the Caliphate
lasted.[30] The building lasted three years and was completed in the
year 149 (A.D. 766). That year is really the