Sun Tzu: The Art of War (II): Waging War

I will use this easily accessible translation version
to comment on The Art of War, and I will pretend that Sun Tzu was indeed a historical person. 
Sun Tzu artist's impression from Qīnggōngdiàn Cánghuàběn
清宮殿藏畫本 / 清宫殿藏画本

II. Waging War

1. Sun Tzu said: In the operations of war, where there are in the field a thousand swift chariots, as many heavy chariots, and a hundred thousand mail-clad soldiers, with provisions enough to carry them a thousand li, the expenditure at home and at the front, including entertainment of guests, small items such as glue and paint, and sums spent on chariots and armor, will reach the total of a thousand ounces of silver per day. Such is the cost of raising an army of 100,000 men.

The enormous costs of raising an army have been superseded by the enormous costs of maintaining an army. The purchasing of hardware is nowadays a rather small part of an army budget compared to the personnel expenses.
Even very expensive platforms such as self-propelled guns or tanks have to be designed and selected with a diligent calculation of life-cycle costs. A single crewmember difference (such as by the choice of using an autoloader or not) can decide which platform concept is the better choice, especially after taking into account overhead costs. It is a regrettable side-effect that army bureaucracies can manipulate this to make a favoured design look superior. The internal rate of return and other assumptions can be manipulated to reach a desired outcome.

2. When you engage in actual fighting, if victory is long in coming, then men's weapons will grow dull and their ardor will be damped. If you lay siege to a town, you will exhaust your strength.

Industrial warfare tends to see a great improvement of the equipment over the course of a multi-year war rather than weapons getting 'dull'. A Me 262A-1a fighter of 1945 was a generation ahead of a Bf 109E-1 fighter of 1939 and a Panther D of 1945 a generation ahead to a Pzkpfw IVc of 1939, for example. Germany also had more Bf 109 fighters by the end of WW2 than at its start, in addition to other new fighter types. American of troops began the occupation of Afghanistan and Iraq in 2002 and 2003 with vehicles unfit for the purpose, and a few years later they had thousands of tailored MRAP vehicles.

We have developed propaganda if not mass hysteria and various forms of extremism to motivate and fanaticise troops. War weariness has happened (examples 1917/1918 front in France, crumbling Russian Army after the Brussilov offensives), but overall the modern way of waging war has learned to motivate for long war since the French Revolutionary Wars. Other wars (such as some modern occupations and 18th century cabinet wars) appear to keep going without good troops morale or much motivation, simply by political inertia and a continuing influx of vastly superior resources.

I mentioned the siege issue earlier.

3. Again, if the campaign is protracted, the resources of the State will not be equal to the strain.

States have developed into much more robust and sophisticated concepts since. Up to the 18th century war financing war often depended on an accumulated crown treasure that would become depleted during wartime, leading to a reduction of active forces to a level that could be sustained with the ongoing revenues and some loans. Wars of the 20th century have been waged by states with existing public debt and little financial reserves. 
Total war has mobilised so much of a country's economy that enormous efforts such as 10+% of the population in arms have become feasible and been sustained for years.
Long-term public and private investments get neglected in major wars. A quasi-mobilized country may sustain a ridiculously expensive military power for decades, but this consumes substance and reduces economic growth. The Soviet Union and North Korea were examples of countries trying to compete with a huge (perceived) military threat despite having a much-inferior economic base, and the result was ruin.
Western countries with much military spending relative to their economy tend to neglect research and public infrastructure while growing the national public debt due to an unwillingness to acquire the needed money by taxation rather than by promises of returns with interest.

4. Now, when your weapons are dulled, your ardor damped, your strength exhausted and your treasure spent, other chieftains will spring up to take advantage of your extremity. Then no man, however wise, will be able to avert the consequences that must ensue.

This is a theoretical possibility and German leadership had to fear this in 1939/1940. A long and exhausting war with France and the UK would have left Germany ill-prepared to defend against the "Bolshevists" in the East.
Yet military history practice is that defeated countries have little left to take from them and "winning" countries have built up so much military strength during the war that such opportunistic attacks on exhausted states aren't much of a thing in industrialised warfare. Italy tried it in 1915, and clearly got the timing all wrong.

5. Thus, though we have heard of stupid haste in war, cleverness has never been seen associated with long delays.

Nowadays we don't have so much a problem with too ponderous campaigning, but rather with extremist expectations preventing a conclusion to the war. We might have a problem with too slow decision-making and order dissemination if we were to fight conventional land warfare, though.

6. There is no instance of a country having benefited from prolonged warfare.

Except maybe the Mongols and countries not directly involved in the war, of course.
Again, the problem is not so much the will to get the war done quickly as the unwillingness to accept compromises to actually end it.

7. It is only one who is thoroughly acquainted with the evils of war that can thoroughly understand the profitable way of carrying it on.

War isn't "profitable" to those involved. It's destructive and consuming, not productive. The last "profitable" European war regarding war booty or reparations ended in 1871. The last "profitable" European war regarding territorial gains ended in 1913 unless you count the Krajina campaign (1995) and annexation as a separate war.

8. The skillful soldier does not raise a second levy, neither are his supply-wagons loaded more than twice.

Sun Tzu offers a rule of thumb and essentially this rule of thumb is aimed against mission creep. It shall force the strategist to stick to the original idea for the extent of the war, which in turn requires the strategist to accept compromises to conclude the war fairly early on.

Loosely related; Nazi Germany raised army divisions in waves. The first four waves were pre-planned in peacetime, and already showed a decline in quality from 1st to 4th, especially in regard to motor vehicle equipment and increasing age of soldiers. An incompetent leadership more interested in delusions of nominal strength rather than in actual strength kept raising more divisions when the existing ones couldn't be filled up and supplied any more. There were a total of 35 waves.

9. Bring war material with you from home, but forage on the enemy. Thus the army will have food enough for its needs.

Food is the least of the supply needs nowadays. Fuels and munitions are utterly dominant in modern conventional warfare. You can usually forage fodder in an invaded land, but it's a lot more tricky to source thermal sight replacement parts or 5.56x45 mm cartridges there. 
You should also understand that during the time of Sun Tzu the draft animals were requiring much more food than the soldiers. The soldiers' food was important for morale and for health, but the bulk and mass of the horse fodder was much more of a problem. Some armies - such as cavalry-dependent armies of Mongols - could not stay and operate in certain areas for long for want of horse fodder and grazing areas.

10. Poverty of the State exchequer causes an army to be maintained by contributions from a distance. Contributing to maintain an army at a distance causes the people to be impoverished.

11. On the other hand, the proximity of an army causes prices to go up; and high prices cause the people's substance to be drained away.

Historical armies often resupplied themselves with food by tolerating an appendix of marketers. These marketers would source food and shoes and so on the in the vicinity of the army and sell everything to the troops and army-following civilians. The suddenly increased local demand led to the local inflation mentioned by Sun Tzu. The poorest civilians in the area would not be able to afford the goods that the troops demand as well.

12. When their substance is drained away, the peasantry will be afflicted by heavy exactions.

13,14. With this loss of substance and exhaustion of strength, the homes of the people will be stripped bare, and three-tenths of their income will be dissipated; while government expenses for broken chariots, worn-out horses, breast-plates and helmets, bows and arrows, spears and shields, protective mantles, draught-oxen and heavy wagons, will amount to four-tenths of its total revenue.

Some modern states such as the U.S. federal government are essentially giant insurance companies with a military, and very little else. This was even more extreme before government-run social insurances were invented in the late 19th century. The absolutist regimes of the 18th century often had more than 80% of their spending in the military realm (there was no real budgeting because they had no separation of powers with a legislative branch giving a budget to the executive branch).

15. Hence a wise general makes a point of foraging on the enemy. One cartload of the enemy's provisions is equivalent to twenty of one's own, and likewise a single picul of his provender is equivalent to twenty from one's own store.

Again, the characteristics of horse (or ox) cart logistics are important here. A rule of thumb was that horse-drawn carts could only supply an army reasonably well out to 250 km from a depot or port. The horses ate so much fodder that you would have to load the cart almost exclusively with fodder for a two-way trip if the distance was much greater. This made canals and seaports as well as drawing food and fodder locally so important.
Moreover, maintaining a huge army in one region required the dispatch of elements to source food and fodder from elsewhere. The disastrous Byzantine defeat at Manzikert (1071) was preceded by an unheard-of accumulation of forces and a necessity to send many troops away to get food from far away provinces.

16. Now in order to kill the enemy, our men must be roused to anger; that there may be advantage from defeating the enemy, they must have their rewards.

Troops taking war booty has rather fallen out of fashion. Ransoms for captured noblemen and captured professional soldiers were common in Europe for centuries, but this led to extremely undesirable actions when the troops were suddenly focused on prisoners rather than on carrying on the battle. One countermeasure was a commanded massacre of prisoners (Swiss, Englishmen in the 100 Years War), but that led to obviously undesirable repercussions.

17. Therefore in chariot fighting, when ten or more chariots have been taken, those should be rewarded who took the first. Our own flags should be substituted for those of the enemy, and the chariots mingled and used in conjunction with ours. The captured soldiers should be kindly treated and kept.

The Romans knew a special medal for the soldier who arrived at the wall of a stormed city first. The greed for such rather immaterial prestige rewards is still getting exploited with medals. It did lead to some very undesirable excessively aggressive actions. Officers should probably be excluded from such incentives schemes, for they were prone to dangerous medal-horny behaviour in the 19th and 20th century.

18. This is called, using the conquered foe to augment one's own strength.

Captured gear is very important to the side with the inferior economic resources in industrial warfare. Germany did it extensively in WW2 and some guerilla movements built their equipment strategy almost entirely on capturing or buying (from corrupt troops) government equipment.

19. In war, then, let your great object be victory, not lengthy campaigns.

This seems obvious, but keep in mind that the Neocons believed they could wage half a dozen wars in the time they actually ended up blundering in Iraq and Afghanistan. The wish for a quick end to a war means nothing if you aren't willing to accept compromises.
Moreover, we would rather say "mission" now than "victory".

20. Thus it may be known that the leader of armies is the arbiter of the people's fate, the man on whom it depends whether the nation shall be in peace or in peril.

Not really, but this was already covered in part I.



  1. "When you engage in actual fighting, if victory is long in coming, then men's weapons will grow dull and their ardor will be damped. If you lay siege to a town, you will exhaust your strength."

    You interpret this technologically. There's also a psychological interpretation, because even in Sun Tzu's time weapons could be sharpened during a long campaign. The longer a conflict lasts, the less enthusiastic it is waged, would be my interpretation of these lines.

    1. That would be the "ardor" part and I wrote in the second comment paragraph about this.
      I interpret the "dull" part as being about an actual material (and livestock) degradation of the army. Clothes (shoes!) get worn-out, carts break down, tents rip, draft animals fail, shields and spears get damaged and so on.

      Weirdly, he did not mention the personnel losses to desertion and infectious diseases here. Nor did he mention that men may actually lose muscle mass when they have great exertions for months with insufficient nourishment.