The outer sections went first.
Riders on the left end of Berke's remaining center, the ones who had been in contact longest, whose horses were blown and whose arms were past controlled work, turned and went south.
A handful of them. Then more. The officers nearest to them shouted and some stopped and some did not, and the ones who did not stop were at a full canter within three strides.
Batu saw it from where he stood on the south bank.
The gap that opened on the left end was small at first. Six men, ten.
The Jochid riders coming over the far lip pressed into the space before the officers could fill it. A man in Berke's remaining front tried to cover the gap by moving laterally and a shaft from close range found him in the shoulder.
He lurched forward onto his horse's neck and the gap stayed open and the riders behind him stopped watching their officers.
More men turned on that side.
The officers in the center were still holding it. Their presence was the instrument.
