"Allah watered the dead with the relentless Euphrates,
And others in the middle areas of Najaf."
[ Al-Qa'qa' bin Amr, commander in Khalid's army]1
The third great battle with the Persians had been won, and Khalid was nearer his ultimate objective-Hira. But he still had far to go and had no illusions about the journey. It was unlikely that the proud Persians would withdraw from his path. Much blood must yet be shed.
In spite of his masterly manoeuvre and his best efforts, a few thousand enemy warriors did manage to escape from the Battle of Walaja. They were mainly Christian Arabs from the tribe of Bani Bakr (Muthanna's tribe-those elements which had not accepted the new faith and had clung to Christianity). Much of this tribe lived in Iraq, as Persian subjects. They had responded to the call of Andarzaghar and with him they had fought and suffered at Walaja.
These Arab survivors of Walaja, fleeing from the battlefield, crossed the River Khaseef and moved between it and the Euphrates (the two rivers were about 3 miles apart, the former being a branch of the Euphrates). Their flight ended at Ullais, about 10 miles from Walaja (see Map 10). Here they felt reasonably safe, as the place was on the right bank of the Euphrates, and on the other side of Ullais ran the Khaseef, which actually took off from the Euphrates just above Ullais. Ullais could only be approached frontally, i.e. from the south-east.2
For a few days Khalid rested his exhausted troops and himself remained busy with the distribution of the spoils and preparations for the onward march. Knowing of the existence of Bahman's army, he could appreciate that another bloody battle would have to be fought before he got to Hira. Since the centre of gravity of the campaign in Iraq had now shifted from the Tigris to the Euphrates, he recalled the Muslim detachments which he had left on the lower Tigris.
Khalid knew from his agents about the presence of hostile Arabs at Ullais; but since they were only the survivors of Walaja he did not consider them a military problem. In any case, he did not wish to over-strain his men by rushing them into another battle before they had recovered from their great trial of strength with Andarzaghar. But when about 10 days later he was informed of the arrival of more Arab forces at Ullais, it became evident that he would have to deal with a complete and almost new army. The hostile concentration was large enough to promise a major battle. As soon as his detachments from the lower Tigris had joined him, Khalid set off from Walaja with an army whose strength, as at the time of its entry into Iraq, was 18,000 men.3 Since there was no way of getting to Ullais from a flank because of the two rivers, Khalid had no option but to cross the Khaseef and approach his objective frontally.
The annihilation of the army of Andarzaghar, following close upon the heels of Kazima and the River, shook the Empire of the Chosroes to its foundations. There appeared to be an unearthly quality about this Army of Islam which had emerged like an irresistible force from the desert. Any Persian army that opposed its relentless march vanished. For the proud Persian court, accustomed to treating the dwellers of the desert with contempt, this was a bitter pill to swallow. Never before in its long history had the empire suffered such military defeats, in such rapid succession, at the hands of a force so much smaller than its, own armies, so close to its seat of power and glory.
For the first time the Persians found it necessary to revise their opinions about the Arabs. It was clear that there was something about Islam which had turned this backward, disorganised and unruly race into a powerful, closely-knit and disciplined force of conquest. And it was clear also that there was something about this man Khalid-whose name was now whispered with fear in Persian homes-that added a touch of genius to the operations of his army. But a grand empire of 12 centuries is not beaten with three battles. The Persians were a race of conquerors and rulers who had lost battles before and risen again. The mood of dismay which had gripped Ctesiphon at the first reports of Walaja passed, and was replaced by a single-minded determination to crush this invading army and fling it back into the desert whence it came. Persia picked herself up, dusted herself, and prepared for another round.
1. Ibn Kathir, Al-Bidayah wan-Nihayah, Dar Abi Hayyan, Cairo, 1st ed. 1416/1996, Vol. 6 P. 425.
2. According to Tabari (Vol. 2, P. 560), Ullais was at a junction of the Euphrates. Musil (p. 193) places it at Ash-Shasi, which is now known as Al Asi and is 4 miles west-north-west of Shinafiya. Even now the place can only be approached from between the two rivers, unless one uses a boat to cross one of them.
3. Tabari: Vol. 2, p. 562. There is no record of reinforcements, but the Muslim losses must have been made up by either reinforcements from Arabia or local volunteers from Iraq.