How many troops were there in March?

During the Spring and Autumn Period, marching operations were divided into three armies: left, right, middle or upper, middle and lower. The main commander was under the command of the Chinese army, and later people called him the main commander. The former army explored the road for the big troops; Zhong Jun is the main force; Rear troops, grain, grass, etc. And provide escort for large troops. Zuo Jun and the army on the right protected the two wings of the large army and coordinated their actions.