Generally, the requirements of warfare are this way:
One thousand quick four-horse chariots,
one thousand leather rideable chariots,
one hundred thousand belted armor,
transporting provisions one thousand li,
the distribution of internal and on the field spending,
the efforts of having guests, materials such as glue and lacquer,
tributes in chariots and armor,
will amount to expenses of a thousand gold pieces a day.
Only then can one hundred thousand troops be raised.
When doing battle, seek a quick victory.
A protracted battle will blunt weapons and dampen ardor.
If troops lay siege to a walled city, their strength will be exhausted.
If the army is exposed to a prolonged campaign, the nation's resources will not suffice.
When weapons are blunted, and ardor dampened, strength exhausted, and resources depleted, the neighboring rulers will take advantage of these complications.
Then even the wisest of counsels would not be able to avert the consequences that must ensue.
Therefore, I have heard of military campaigns that were clumsy but swift, but I have never seen military campaigns that were skilled but protracted.
No nation has ever benefited from protracted warfare.
Therefore, if one is not fully cognizant of the dangers inherent in doing battle, one cannot fully know the benefits of doing battle.
Those skilled in doing battle do not raise troops twice, or transport provisions three times.
Take equipment from home but take provisions from the enemy.
Then the army will be sufficient in both equipment and provisions.
A nation can be impoverished by the army when it has to supply the army at great distances.
When provisions are transported at great distances, the citizens will be impoverished.
Those in proximity to the army will sell goods at high prices.
When goods are expensive, the citizens' wealth will be exhausted.
When their wealth is exhausted, the peasantry will be afflicted with increased taxes.
When all strength has been exhausted and resources depleted, all houses in the central plains utterly impoverished, seven-tenths of the citizens' wealth dissipated,
the government's expenses from damaged chariots, worn-out horses, armor, helmets, arrows and crossbows, halberds and shields, draft oxen, and heavy supply wagons,
will be six-tenths of its reserves.
Therefore, a wise general will strive to feed off the enemy.
One bushel of the enemy's provisions is worth twenty of our own, one picul of fodder is worth twenty of our own.
Killing the enemy is a matter of arousing anger in men;
taking the enemy's wealth is a matter of reward.
Therefore, in chariot battles, reward the first to capture at least ten chariots.
Replace the enemy's flags and standards with our own.
Mix the captured chariots with our own, treat the captured soldiers well.
This is called defeating the enemy and increasing our strength.
Therefore, the important thing in doing battle is victory, not protracted warfare.
Therefore, a general who understands warfare is the guardian of people's lives, and the ruler of the nation's security.