o some other position, either
to Istakr, the ancient metropolis of Persia Proper, or to Hamadan, the
capital city of Media. But probably it was considered that to retire
voluntarily from the Tigris would be a confession of weakness, as fatal
to the stability of the empire as to be driven back by the Arabs; and
perhaps it may have been hoped that the restless nomads would be content
with their existing conquests, or that they might receive a check at the
hands of Rome which would put a stop to their aggressions elsewhere.
It is remarkable that, during the pause of a year and a half which
intervened between the battle of Kadisiyeh and the resumption of
hostilities by the Arabs, nothing seems to have been done by Persia in
the way of preparation against her terrible assailants.

In the year A.D. 637 the Arabs again took the offensive. They had
employed the intervening year and a half in the foundation of Busrah and
Kufam and in the general consolidation of their sway on the right bank
of the Euphrates. They were now prepared for a further movement. The
conduct of the war was once more entrusted to Sa'ad. Having collected
an army of 20,000 men, this general proceeded from Kufa to Anbar
(or Perisabor), where he crossed the Euphrates, and entered on the
Mesopotamian region. Isdigerd. learning that he had put his forces in
motion, and was bent upon attacking Ctesiphon, called a council of
war, and asked its advice as to the best course to be pursued under
the circumstances. It was generally agreed that the capital must be
evacuated, and a stronger situation in the more mountainous part of the
country occupied; but Isdigerd was so unwilling to remove that he waited
till the Arabian general, with a force now raised to 60,000, had reached
Sabat, which was only a day's march from the capital, before he could
be induced to commence his retreat. He then abandoned the town hastily,
without carrying off more than a small portion of the treasures which
his ancestors had during four centuries accumulated at the main seat
of their power, and retired to Holwan, a strong place in the Zagros
mountain-range. Sa'ad, on learning his movement, sent a body of troops
in pursuit, which came up with the rear-guard of the Persians, and cut
it in pieces, but effected nothing really important. Isdigerd made good
his retreat, and in a short time concentrated at Holwan an army of above
100,000 men. Sa'ad, instead of pushing forward and engaging this forc