On receiving the orders of the Caliph, Khalid at once undertook preparations to raise a new army. His riders galloped far and wide in the region of Yamamah and in Central and Northern Arabia, calling brave men to arms for the invasion of Iraq. And brave men assembled in thousands, many of them his old comrades of the Campaign of the Apostasy who, having visited their homes, decided to return to his standard for fresh adventure and glory. Khalid's name was now a magnet that drew warriors to him. Fighting under Khalid meant not only victory in the way of Allah, but also spoils and slaves ... in fact the best of both worlds! Within a few weeks an army of 10,000 men was ready to march with Khalid.2
There were four important Muslim chiefs with large followings in North-Eastern Arabia, Muthanna bin Harithah, Mazhur bin Adi, Harmala and Sulma. The first two of these have already been mentioned in the preceding chapter. The Caliph had written to them to muster warriors and operate under the command of Khalid. Now Khalid wrote to all four of them, informing them of his appointment as commander of the Muslim army and of the mission which he had received from the Caliph. He ordered them to report to him, along with their men, in the region of Uballa. It is believed that Muthanna, who was at, Khaffan at the time (a place 20 miles south of Hira)3 was displeased with the arrangement. He had hoped that the Caliph would give him a large independent command in Iraq, as he certainly deserved; but he came as ordered, and placed himself and his men at the disposal of Khalid. He was to prove the best of subordinate commanders.
Each of these four chiefs brought 2,000 men. Thus Khalid entered Iraq with 18,000 warriors4 -the largest Muslim army yet assembled for battle.
In about the third week of March 633 (beginning of Muharram, 12 Hijri), Khalid set out from Yamamah. But before doing so he wrote to Hormuz, the Persian governor of the frontier district of Dast Meisan:
Submit to Islam and be safe. Or agree to the payment of the Jizya, and you and your people will be under our protection, else you will have only yourself to blame for the consequences, for I bring a people who desire death as ardently as you desire life.5
Hormuz read the letter with a mixture of anger and contempt, and informed the Persian Emperor Ardsheer of Khalid's threat. He made up his mind to teach these crude Arabs a lesson that they should never forget.
Khalid began his advance from Yamamah with his army divided into three groups. He did this in order not to tire his men or waste time by having too many troops in the same marching column. Each group set off a day apart. Thus each group was a day's march from the next, far enough for ease of movement, and yet close enough to be swiftly concentrated for battle if required. Khalid himself moved with the third group on the third day. The whole army would concentrate again near Hufair6 ; and before leaving Yamamah he promised his men a great battle with Hormuz.
1. Ibn Kathir, Al-Bidayah wan-Nihayah, Dar Abi Hayyan, Cairo, 1st ed. 1416/1996, Vol. 6 P. 425.
2. Tabari: Vol. 2, p. 554.
3. Musil (p. 284) places Khafran 20 kilometres south-east of Qadissiyah. It was at or near the present Qawam which is six miles west of Shinafiya.