Hence that general is skilful in attack whose opponent does not know what to defend; and he is skilful in defense whose opponent does not know what to attack.
A clever general... avoids an army when its spirit is keen, but attacks it when it is sluggish and inclined to return. This is the art of studying moods. Disciplined and calm, he awaits the appearance of disorder and hubbub among the enemy. This is the art of retaining self-possession.
Use humility to make the enemy haughty. Tire them by flight. Cause division among them. When they are unprepared, attack and make your move when they do not expect it.
From a position of this sort, if the enemy is unprepared, you may sally forth and defeat him. But if the enemy is prepared for your coming, and you fail to defeat him, then, return being impossible, disaster will ensue.
Be the first to seize intersecting ground, that is ground which lies the intersections of borders or intersections of main thoroughfares of commerce and travel. Your occupation of it gives you access to all who border it and all who would covet it. On intersecting ground, if you establish alliances you are safe, if you lose alliances you are in peril.
The sovereign must have full knowledge of the activities of the five sorts of agents. This knowledge must come from the double agents, and therefore it is mandatory that they be treated with the utmost liberality.