31. If the enemy sees an advantage to be gained
Not necessarily “booty,” as Capt. Calthrop translates it. The T‘ung Tien and Yü Lan read 向人見利, etc.
and makes no effort to secure it, the soldiers are exhausted.
32. If birds gather on any spot, it is unoccupied.
A useful fact to bear in mind when, for instance, as Ch‘ên Hao says, the enemy has secretly abandoned his camp.
Clamour by night betokens nervousness.
Owing to false alarms; or, as Tu Mu explains it: 恐懼不安故夜呼以自壯也 “Fear makes men restless; so they fall to shouting at night in order to keep up their courage.” The T‘ung Tien inserts 喧 before 呼.
33. If there is disturbance in the camp, the general's authority is weak. If the banners and flags are shifted about, sedition is afoot.
The T‘ung Tien and Yü Lan omit 旌.
If the officers are angry, it means that the men are weary.
And therefore, as Capt. Calthrop says, slow to obey. Tu Yu understands the sentence differently: “If all the officers of an army are angry with their general, it means that they are broken with fatigue” [owing to the exertions which he has demanded from them].
34. When an army feeds its horses with grain and kills its cattle for food,
粟馬肉食 is expanded by Mei Yao-ch‘ên following Tu Mu into 給糧以𥞊乎馬殺畜以饗乎士, which is the sense I have given above. In the ordinary course of things, the men would be fed on grain and the horses chiefly on grass.
and when the men do not hang their cooking-pots