SUN ZI said:  Normally, in war, the general receives ms commands from the sovereign. During the process from assembling the troops and mobilizing the people to deploying the army ready for battle, nothing is more difficult than the art of manoeuvring for seizing favourable positions  beforehand.  What is difficult about it is to make the devious route the most direct and to turn disadvantage to advantage.  Thus, forcing the enemy to deviate and slow down his march by luring him with a bait, you may set out after he does and arrive at the battlefield before him.  One able to do this shows the knowledge of artifice of deviation.

    Thus, both advantage and danger are inherent in manoeuverlng for an advantageous position.  One who sets the entire army in motion with impedimenta to pursue an advantangeous position will be too slow to attain it.  If he abandons the camp and all the impedimenta to contend for advantage, the baggage and stores will be lost.  It follows that when the army rolls up the armour and sets out speedily, stopping neither day nor night and marching at double speed for a hundred Ii to wrest an advantage, the commander of three divisions will be captured.  The vigorous troops will arrive first and the feeble will straggle along behind, so that if this method is used only one-tenth of the army will arrive.  In a forced march of fifty li the commander of the first and van division will fall, and using this method but half of the army will arrive.  In a forced march of thirty Ii, but two-thirds will arrive.  Hence, the army will be lost without baggage train; and it cannot survive without provisions, nor can it last long without sources of supplies.

    One who is not acquainted with the designs of his neighbours should not enter into alliances with' them.  Those who do not know the conditions of mountains and forests, hazardous defiles, marshes and swamps, Cannot conduct the march of an army.  Those who de not use local guides are unable to obtain the advantages of the ground.  Now, war is based on deception.  Move when it is advantageous and change tactics by dispersal and  concentration of your troops.  When campaigning, be swift as the wind; in leisurely march, majestic as the forest; in raiding and plundering, be fierce as fire; in standing, be firm as the mountains.  When hiding, be as unfathomable as things behind the clouds; 'when moving, fall like a thunderclap.  When you plunder the  countryside, divide your forces.  When you conquer territory, defend strategic points. Weigh the situation before you move.  He who knows the artifice of deviation will be victorious.  Such is the art of manoeuvring.

    The Book of Army, Management says:  'As the voice cannot be heard in battle, gongs and drums are used.  As troops cannot see each other clearly in battle, flags and banners are used.' Hence, in night fighting, usually use drums and gongs; in clay fighting, banners and flags.  Now, these instruments are used to unify the action of the troops.  When the troops can be thus united, the brave cannot advance alone, nor can the cowardly retreat.  This is the art of directing large masses of troops.

    A whole army may be robbed of its spirit, and its commander deprived of his presence of mind.  Now, at the beginning of a campaign, the spirit of soldiers is keen; after a certain period of time, it declines; and in the later stage, it may be dwindled to nought.  A clever commander, therefore, avoids the enemy when his spirit is keen and attack him when it is lost.  This is the art of attaching importance to moods.  In good order, he awaits a disorderly enemy; in serenity, a clamorous one. This is the art of retaining self-possession.  Close to the field of battle, he awaits an enemy coming from afar; at rest, he awaits an exhausted enemy; with well-fed troops, he awaits hungry ones.  This is the art of husbanding one's strength. He refrains from intercepting an enemy whose banners are in perfeet order, and desists from attacking an army whose formations are in an impressive array.  This is the art of assessing circumstances.

    Now, the art of employing troops is that when the enemy occupies high ground, do not confront him uphill, and when his back is resting on hills, do not make a frontal attack.  When he pretends to flee, do not pursue.  Do not attack soldiers whose temper is keen. Do not swallow a bait offered  by the enemy.  Do not thwart an enemy who is returning homewards.  When you surround an army, leave an outlet free.  Do not press a desperate enemy too hard. Such is the method of using troops.