Generally in the method of warfare, the fundamental principle consists in making government measures supremely prevalent. If this is done, then the people concerned will have no disputes; and having no disputes, they will have no thought of self-interest, but will have the interest of the ruler in mind. Therefore a real king, through his measures, will cause people to be fearful in fights between various cities, but brave in wars against external foes. If people have been trained to attack dangers with energy, they will, as a result, think lightly of death. Should the enemy be routed as soon as the engagement has begun, and should he not stop in his rout, abstain from further pursuit. Therefore does the "Art of War" say: ’In a big battle, in the event of victory, pursue the fugitives not further than 10 li; in a small battle, in the event of victory, pursue the fugitives not further than 5 li.’ When hostilities begin, weigh the strength of the enemy; if your organization is not equal to his, do not engage him in battle; if your provisions are not equal to his, do not protract the war; if the enemy is numerically strong, do not invade his territory; if the enemy is in every way your inferior, attack him without hesitation. Therefore it is said: ’The great rule of an army is prudence.’ By estimating the strength of the enemy and by examining one’s own hosts, victory or defeat may be known beforehand.
The army of a real king does not boast of victory, nor does it harbour rancour for defeat. That it does not boast of victory is because it ascribes it to its clever tactics; that it does not harbour rancour for defeat is because it knows why it has failed. If the relative strength of the armies is well-matched, the side that has clever leadership will win, and the side that has inferior leadership will lose. If the organization has its origin in the calculations made in the temple, then it will win, whether the leadership is clever or inferior. He who holds victorious tactics will be so strong that he will attain supremacy. If people are submissive and obey their ruler, then the country will become rich and the army victorious; and if this state of affairs is maintained for long, he will surely attain supremacy. But it is a mistake for an army to penetrate deeply into the enemy’s country, in difficult and unsurmountable terrain and cut off in a cul-de-sac; the men will become exhausted, hungry and thirsty as well, and will, moreover, fall victims to disease. This is the way to defeat. Therefore he who intends to direct the people... and he who mounts a good horse cannot but be on his guard.