8. 若交軍於斥澤之中必依水草而背衆樹此處斥澤之軍也
If forced to fight in a salt-marsh, you should have water and grass near you, and get your back to a clump of trees.
Li Ch‘üan remarks that the ground is less likely to be treacherous where there are trees, while Tu Yu says that they will serve to protect the rear. Capt. Calthrop, with a perfect genius for going wrong, says “in the neighbourhood of a marsh.” For 若 the T‘ung Tien and Yü Lan wrongly read 爲, and the latter also has 倍 instead of 背.
So much for operations in salt-marshes.
9. 平陸處易而右背高前死後生此處平陸之軍也
In dry, level country, take up an easily accessible position
This is doubtless the force of 易, its opposite being 險. Thus, Tu Mu explains it as 坦易平穩之處 “ground that is smooth and firm,” and therefore adapted for cavalry; Chang Yü as 坦易無坎陷之處 “level ground, free from depressions and hollows.” He adds later on that although Sun Tzŭ is discussing flat country, there will nevertheless be slight elevations and hillocks.
with rising ground to your right and on your rear,
The Yü Lan again reads 倍 for 背. Tu Mu quotes T‘ai Kung as saying: “An army should have a stream or a marsh on its left, and a hill or tumulus on its right.”
so that the danger may be in front, and safety lie behind.