Applying Art to the Total War: Waging War

Waging War: Waging war is the second of the 13 points of the book. the author is not as specific in the subdivisions of the topic as he is in the first part of the book. I'll point out some advices and then compare them to the game.
Sun Tzu says that "there is no instance of a country having benefited from prolonged warfare". This fits in the game up to a certain extent. Though the player can attempt and many times success in being in peace with the neighbouring reigns, sooner or later someone is going to attack you, and you need to be prepare and to have a regular army to respond swiftly to the attack.
What Sun Tzu enphasizes in this part of the book is that provisions shoould be taken from the enemy, thus you save money by not bringing it from home. that lengthy campaigns are not profitable, and having the chance to forage the enemy's land, a soldier has to do it. In the game, there is no such a thing as provisions for the soldier or foraging the land, but after a siege and if it results in victury, the player can either occupy the settlement, sack it (great income) or exterminate the population. The last two give a bonus to law and order by inflicting fear. 

Every unit has a fixed upkeep cost, so it does not matter where your troops are, they will always "suck" the same amount of resources. Another factor that might affect how long you wage a war against another nation, is that in order to "win" in the game, the player has to have under control a certain amount of provinces, therefore if attacked, then you concentrate all your troops in attacking and conquering the other faction. But sometimes you have to stop the bloodshed because the POPE! asks you to do it, otherwise you might be excommunicated and if it's already difficult to wage war against one nation, waging it against all Christendom will not help you at all.