9. The Army on the March

3

After crossing a river, you should get far away from it.

"In order to tempt the enemy to cross after you," according to Ts`ao Kung, and also, says Chang Yu, "in order not to be impeded in your evolutions." The T`UNG TIEN reads, "If THE ENEMY crosses a river," etc. But in view of the next sentence, this is almost certainly an interpolation.