Note 161 — Chapter XI · CAMPAIGN IN SYRIA.—BATTLE OF WACUSA ON THE YERMUK. A.H. XIII. A.D. 634.

The numbers of Khâlid’s column are variously stated at 9,000 and 6,000; and again as low as 800, 600, and 500. But the smaller numbers are probably intended to indicate only that part of his force which formed the flying column in his adventurous march across the desert: the rest, I assume, followed more leisurely and by an easier route. In point of fact, 6,000 returned the following year to Irâc, though they had been thinned by the Syrian campaign.

Some put the march of Khâlid a month earlier. Ibn Ishâc says that before leaving, Khâlid despatched the sick and infirm, with the women and children, to Medîna, with the last consignment of royal prize, as if he apprehended insecurity during his absence.