These are the methods of employing troops.
[VIII]
THE NINE CHANGES
Sun the Master said:—
In general, the procedure of war is:—the Leader, having received orders from his lord, assembles the armies.
Do not camp on marshy or low-lying ground; enter into friendly relations with neighbouring states; do not linger in a far country; use stratagem in mountainous and wooded country; on death ground, fight.
There are always roads that must be avoided; forces that must not be attacked; castles that must not be besieged; ground that must not be chosen for encounter; orders from the lord that must not be obeyed.
The general who knows the Nine Changes understands the use of troops; on the contrary, he who does not understand them, can make no use of his topographical knowledge.
In the management of armies, if the art of the Nine Changes be understood, a knowledge of the Five Advantages is of no avail.
The wise man considers well both advantage and disadvantage. He sees a way out of adversity, and on the day of victory to danger is not blind.