Sun Tzu: The Art of War (5th century BC)

(Source)

Quotes

  • “Those who master them win; those who do not are defeated.”
  • “All warfare is based on deception.”
  • “For there has never been a protracted war from which a country has benefited.”
  • “One defends when his strength is inadequate; he attacks when it is abundant.”
  • “A victorious army wins its victories before seeking battle.”
  • “A skilled commander seeks victory from the situation and does not demand it of his subordinates.”
  • “An army may be likened to water.”

Chapter 1: Estimates

Sun Tzu begins his instruction on the topic of estimates in this first chapter with a brief introduction. He states it is of utmost importance that war be “thoroughly studied,” because its outcome means the difference between survival or ruin of the state. He discusses five fundamental factors: moral influence, weather, terrain, command, and doctrine, along with seven elements to be elaborated on later. Sun Tzu then explains what he means by each of these five factors. Commentators then follow with examples and elaborations.

Chang Yu adds that these five fundamental factors combined serve to develop a preconflict plan of action—or strategy—in dealing with rebels. This step-by-step strategy begins with an examination of the relationship of the people to their governance, or what Sun Tzu calls “moral assessment.” The issue is whether or not the people are confident in their ruler, which would determine their ability and willingness to support the stresses of waging a war. Once this estimation has been made, next up are the two related conditions of anticipated weather and the characteristics of the ground over which troops must march to meet and engage the enemy. Distances, and the difficulty or ease of marching over the terrain, must be estimated so that troops arrive in the best condition possible before engaging the enemy. Commentator Mei Yao-ch’en briefly accounts for terrain by stating that an accurate estimate of the conditions surrounding a proposed campaign is important in determining “the advantages of using infantry or cavalry.” (Infantry units fought on foot, while cavalry units were on horseback.)

The last two of the five fundamental factors are command and doctrine. Command estimates have to do with the qualities of the commander that qualify him to order the troops and be certain those orders will be followed. The reputation of the commander must be supported in action, to exhibit the virtues of command as having “wisdom, sincerity, humanity, courage, and strictness.” Closely related to command, the doctrine has to do with “organization, control, assignment of appropriate ranks of officers, regulation of supply routes, and the provision of principle items used by the army.” Sun Tzu makes it clear that this kind of pre-engagement planning offers a greater chance of success than having a large army. He sums up his explanation by saying, “Those who master them win; those who do not are defeated.”

The last part of the chapter explains Sun Tzu’s statement, “All warfare is based on deception.” The more prepared a commander is, the more he should appear to his opponent to be unprepared and disorganized. Tu Mu here offers the example of the Chao general Li Mu who released herds of cattle and gave the appearance of retreat, when in fact his forces were hidden on each side. The opposing Huns fell for the trap, went toward the cattle, and were crushed between the two sides of Li Mu’s troops. The chapter concludes with Sun Tzu’s recommendation that a commander should frequently change tactics by accurately assessing changing conditions.

Chapter 2: Waging War

Sun Tzu discusses the equipment, provisioning, and support of an army sent into battle. He emphasizes the use of both speed and decisiveness to ensure victory, something that cannot be achieved without solid preparation and organization ahead of time. In the interests of making full use of the allocated resources, Sun Tzu strongly recommends that “those adept in waging war do not require a second levy of conscripts nor more than one provisioning.” The commentators weigh in on this idea by providing examples of past campaigns that were successful because the general kept track of both the physical strengths and the state of mind of his troops. They also provide examples of generals who ignored or miscalculated factors such as hunger, thirst, attachment to accumulated loot, or outrage at an injustice that impaired the ability of their troops to fight with decisive speed. The chapter concludes with some overall procedures to follow when capturing enemy troops and their equipment, to maximize the preservation of resources and sustain a well-equipped army.

Chapter 3: Offensive Strategy

In this chapter Sun Tzu states, “To subdue the enemy without fighting is the acme of skill.” Sun Tzu and his commentators return to the goal of subduing and subsuming the enemy—rather than complete destruction—and it is one achieved only through careful planning. Tu Mu quotes the Grand Duke as saying, “He who excels at resolving difficulties does so before they arise.” Sun Tzu then specifies the use of tactics in order of preference, beginning with attacking the enemy’s strategy or plans, then separating the enemy from its allies, followed by attacking the army. The least effective tactic is to lay siege to a city, an act that may be done “only when there is no alternative.”

Control of impatient actions in a siege situation is as critical as it is difficult. As Tu Mu points out in a specific example of a siege gone wrong, Emperor T’ai Wu at the command of 100,000 troops besieged Yu T’ai, which was under the command of the Sung General Tsang Chih. According to custom, the emperor asked Tsang Chih for some wine, but was sent a pot of urine instead. This so enraged the emperor that he attacked the city at once. After 30 days of fighting, over half of the emperor’s army was decimated. Commentator Li Ch’uan adds to this the account of another battle during which rebel forces were entrenched at the city of Yuan Wu, but the attacking army could not take it, even after months of fighting. The attackers fell ill, whereupon their commander was advised to allow the rebels a narrow escape route. That way, when the defenders fled instead of “fighting to the death,” the attackers weakened by illness were able to take the city without a fight, and the rebels disbursed such that “any village constable will be able to capture them.” In every instance, the commander should keep control of both himself and his troops, to prevent them from being needlessly killed.

Sun Tzu also outlines “five circumstances in which victory may be predicted.” These circumstances depend on the commanding general’s knowledge of several things:(1) knowing as much about himself and his own troops as about those of the opposition, so that he will know when to advance and when to retreat; (2) knowing the correct use of both small and large forces; (3) knowing how to forge ranks unified in purpose; (4) knowing how to exercise patience when the opposition does not; and (5) knowing that his sovereign does not interfere with his decisions. The last point is particularly important, as a sovereign’s appointed general is trusted to act with immediate and decisive action under changing conditions on a battlefield. It is therefore up to the sovereign to choose a general in whom he can place his complete trust, while it is the general’s corresponding duty to fulfill the trust placed in him.

Chapter 4: Dispositions

In Chapter 4 Sun Tzu draws a clear distinction between defense and offense, relative to what the general can control (himself and his troops) and what is beyond his control (the opposing general and his troops). He makes several distinctions between effective offensive and defensive tactics. As he explains, “The experts in defense conceal themselves … those skilled in attack move as from above. … Thus they are capable of … protecting themselves and … gaining … victory.” Even so, Sun Tzu goes on to suggest that predicting what seems obvious to “the ordinary man” is sometimes nothing more than misapprehension. Li Ch’uan gives the example of a stunning defeat of the Chao army at the hands of General Han Hsin, who arranged his inferior force in a defensive position with its back to the river to face the Chao troops. Although the Chao army was confident they would be victorious, invisible to them their defeat had already been arranged. The ferocity of the defenders crushed the Chao army, and General Han Hsin beheaded their commander.

Sun Tzu also states that an easy and predictable victory over a clearly inferior force is no mark of skill. At the same time he also warns that what may seem obvious may not actually be so, because victories won before the first clash of troops are sometimes hidden realities, made visible only in the course of battle. In other words, the wise commander prepares well ahead of time by any means possible, ready to take advantage of any opportunity. By way of illustrating this point, commentator Tu Mu quotes Duke Li-Ching of Wei, who describes how the uncertainties of an opposing general can be undermined with “unreliable reports” and lack of planning.

It is in this chapter that Sun Tzu first brings up Taoism as an indicator of how to forge one’s forces into a unit capable of acting like an inevitable force of nature. He also presents calculations to bring this about as “elements of war”: (1) measurement of space, (2) estimation of quantities, (3) calculations, (4) comparisons, and (5) chances of victory. The order in which these are considered is important, because, as he points out, “A victorious army wins its victories before seeking battle; an army destined to defeat fights in the hope of winning.”

Chapter 5: Energy

Sun Tzu turns his attention to the forging of troops into well-organized units that can be skillfully managed to act as a single, irresistible force against a more loosely managed opponent. To support this, commentator Chang Yu describes how a pyramid of command is built from the base at the bottom (individual soldiers) up through each level: pair, trio, squad, section, platoon, company, battalion, regiment, group, brigade, and finally, army. At each level, a commander is appointed to obey his superiors and control his inferiors, with the commanding general at the top.

Proper training and assignment of responsibility at every level is required for consistent functioning, so that control of the battlefield can be immediately established and maintained. This means that, as Chang Yu points out, even though troops may be spread out in the fighting, they and their officers never lose track of when to advance or retreat. These orders are delivered both by sight (“observing flags and banners”) and by sound (“signals of bells and drums”) so that no single individual is ever left alone to either advance or flee.

At this point, Sun Tzu turns to the concept of how to employ both normal forces (requiring less energy) and extraordinary ones (requiring more energy) in a way that will make the enemy uncertain as to which is which. Consistent with his assertion that a quick and decisive blow is preferable to one that extends over a long period of time (Chapters 2 and 3), Sun Tzu advises that the successful general is able to make the enemy believe that the “normal” energy of his army is “extraordinary.” And, given an offensive advantage, the energy of the army opposing them in an extraordinary fashion is really that army’s “normal” mode.

This means, according to Sun Tzu, that a victorious army displays an energy that is “cyclical, as are the movements of the sun and moon.” Thus, the same energy will be applied to any future confrontations as a matter of course. He claims that handling an extraordinary force can be achieved by realizing that its components—like the well-organized and systematic structure of an army—are few, but the possible combinations are limitless. In this respect, Sun Tzu gives the examples of five notes of music and five primary colors that can be arranged in limitless arrangements.

As he did in Chapter 4, Sun Tzu sees forces of nature—such as the momentum of water streaming down a hill, or a hawk striking its prey—as inevitable and irresistible, because given the same situation repeatedly, the same result occurs. The impression that an army cannot be defeated works for the general who can create this impression in his enemies, even when it is not actually the case. When the enemy can be enticed or lured into a risky attack, an advantage can be gained. In this way, a skilled general controls the movements of his enemy instead of being controlled by the enemy.

This chapter concludes with the commentators giving examples of successful deception because the commanding officers obeyed the instructions of their superiors. As Chang Yu concludes, every type of man must be used according to his nature and abilities, including “the avaricious and the stupid.” In this way, a general finds victory in handling both talents and situations, rather than demanding it of his officers.

Chapter 6: Weaknesses and Strengths

Sun Tzu judges a successful general according to his ability to create a situation in which the enemy is forced to engage. This is accomplished by a carrot-and-stick approach in which the enemy is enticed by the illusion of easy success, or pushed into a position from which it can neither adequately defend itself nor completely escape. If forcing the enemy into a trap, Sun Tzu emphasizes that the best way to do this is to leave open what looks like an escape route but is actually a controlled route by which prisoners (and provisions) can be captured.

Most significantly, as Sun Tzu points out, the first army to arrive at the field of battle has the advantage of time to rest, and to fully assess the best positions for their battalions. A general who keeps his opponent in the dark about the details of his plans can cause the opponent to attempt to strengthen one area at the cost of leaving another vulnerable. One way to guarantee success is to have the enemy attempt to fortify in every direction because in so doing, its resources will be spread so thin that no single position would be strong enough to withstand an attack.

Commentator Tu Mu gives an example of how commander Chu-ko Liang left a small force to defend a city, but the attacking general Ssu-ma I was given misleading signs that the defenders were planning an ambush. Assuming the defenders were stronger than he had believed at first, the attacking general fled with his troops into the mountains, only to learn later he had been tricked into calling off a potentially successful attack on the city.

According to Tu Yu, a wise general places separate units of his army at varying distances from the appointed battlefield and orders them to march at different times so they will all arrive together “like people coming to a city market.” So, as Sun Tzu has said in the previous chapter, while signs and signals to one’s own forces must be clear and well understood, those which the enemy is able to read and interpret must lead to false conclusions so that the enemy will act on them, thus compromising its own forces. A general can capitalize on his opponent’s weaknesses, while correspondingly making the best use of his own strengths by constantly changing tactics to fit the conditions of the battle. Sun Tzu concludes the chapter by stating that change is inevitable and that no condition in nature is “always predominant.”

Chapter 7: Maneuver

The second statement Sun Tzu makes at the beginning of this chapter is, “Nothing is more difficult than the art of maneuver.” He expands on this by saying the trick is to make what looks like a convoluted and aimless course into one that is actually direct and focused. He draws a distinction between “direct” and “indirect” approaches designed to simultaneously confuse the enemy and demonstrate the ability in the lower ranks to obey complex and changing commands. Sun Tzu does caution, however, that there are “both advantage[s] and danger” in using this tactic, so it is one only the experienced and seasoned general should attempt.

Tu Mu addresses the art of maneuvering, claiming an army should only split up when absolutely necessary. It is better to make sure all the troops arrive at the battlefield more or less in good condition and at the same time, well ahead of the arrival of the opposing army. This works better if the enemy must rush, which exhausts the troops and supplies along the way. If an army has a long march, those who are strongest and most lightly equipped will arrive first, while the weaker soldiers carrying heavier baggage will straggle behind, leaving themselves open to ambush. Tu Mu cautions that this should be done only “when there is no alternative and you must contend for an advantageous position.”

The entire army gathered together well before the enemy arrives is considered an “advantageous position.” Setting off on an extended forced march with all troops—both strong and weak—and all the equipment, could mean that critical sections of the army are not prepared to face the enemy when they arrive on the battlefield. The longer an army encamps to wait for the arrival of the enemy, the longer the enemy has to strategically size up and evaluate the assembled opposing forces.

Sun Tzu cites The Book of Military Administration to explain the use of banners, gongs, flags, and drums to signal troop movements on the field based on the time of day or night. Tu Mu’s commentary describes how effective castrametation—how a military encampment is laid out in orderly sections—provides protection from nightly attacks. Tu Mu adds that a cluster of smaller encampments surrounding the commander’s headquarters can signal an approaching enemy incursion using torches. This is not just for signaling but also to illuminate the entire camp so the defenders know the location of the enemy.

The discussion then turns to control of the factors introduced in Chapter 1, as they pertain to the relationship between a commanding general and his army. The successful strategy is one that can divide the host of an enemy army from its “head” by controlling the factors of moral, mental, physical, and changing circumstances. The questions Ho Yen-hsi poses point out that all the things that weaken an opposing commander’s confidence and ability to plan must be avoided. The chapter ends with an explanation of how to “bait” a surrounded enemy with a carefully controlled escape route. In one example, Tu Yu describes how the enemy simply ran down the escape route without looking, and offered no resistance. Had they been forced to fight “to the death,” many in the surrounding army would have also been killed or wounded. By treating the enemy like a cornered wild animal, a wise commander positions it for control rather than destruction.

Chapter 8: The Nine Variables

Sun Tzu identifies what should—and should not—be done in five different types of ground to lay a foundation for the nine variables. These kinds of ground are: low-lying (in which an army should not camp), communicating (in which allies may be joined), desolate (to be moved through as quickly as possible), enclosed (requiring resourceful solutions to get out of), and death (in which the only option is to fight).

The nine variables are based on an estimation of changing conditions under which action is either indicated or not indicated in any of the five types of ground. Tu Mu weighs in by referring to the difficulties in attacking a well-provisioned city. Sun Tzu and his commentators emphasize that simply knowing these variables will not do any good; they must be put into immediate action at the required time in order to succeed.

Once the sovereign has placed his confidence in his choice of a commander, that commander must retain complete autonomy and authority on the battlefield. Otherwise, attention to rapidly changing conditions is thwarted, and the enemy is given a chance to take control. Again, it is up to the commander to make the decision regarding what ground to take, when, and how. A careful assessment of possible consequences must be made ahead of time. Chia Lin makes a good point: “Ground … is not to be fought for if one knows … it will be difficult to defend, or that he gains no advantage by obtaining it.”

The chapter concludes with a list of ways to undermine an enemy commander, such as giving him “beautiful women to bewilder him.” Sun Tzu adds that a preoccupation with honor and a compassionate nature are variables to be exploited in an enemy and avoided in a general from whom victory can be expected.

Chapter 9: Marches

This chapter addresses the organization of well-disciplined marches and the arrangement of troops facing an approaching enemy under a variety of conditions. Sun Tzu recommends taking advantage of the positions of sunlight relative not only to time of day but relative to rivers, mountains, salt marshes, and level ground. Ho Yen-hsi references a battle that took place during the Spring and Autumn Annals period. In this incident, the Duke of Sung, whose army had crossed the river, twice stopped his Minister of War from attacking the opposing force before it had crossed and gathered itself to fight on the other side. The result was that “the Sung army was defeated, the Duke wounded in the thigh, and the officers of the Van annihilated.”

Sun Tzu cites the Yellow Emperor as having conquered “four sovereigns” because he took full advantage of encampment opportunities. He recommends taking “the sunny side and rest your right and rear on them.” In addition, placement of an army facing “precipitous torrents” of rivers swollen with rains is an advantage, especially if the opposing army can be forced to place its back against it. This is followed by a list of observable signs that indicate deceptive tactics the enemy might employ. A column of dust, for example, indicates chariots are on the move, whereas infantry movement is indicated by low and wide dust.

Acute observations of signs in nature are important, but Sun Tzu and his commentators add that learning about the enemy’s purposes through the behavior of envoys is also crucial. Commentator Chang Yu gives an example of deceit by T’ien Tan, defender of the city of Chi Mo, when he sent beautiful women and money to lure the attackers. Thinking this event would result in easy pickings, Ch’i Che relaxed his guard enough that T’ien Tan could rush out and “inflict a crushing defeat.”

Ch’en Hao remarks on the effect a lax general has on his troops, stating, “When the general’s orders are not strict and his deportment undignified, the officers will be disorderly.” A general can conduct an interview with one of his spies to assess whether or not there is insubordination within the enemy camp. It is up to the general to maintain consistent and reliable orders down the chain of command to ensure solid support from the troops.

Chapter 10: Terrain

Sun Tzu devotes this chapter to a study of the ground (or terrain) on which a battle may be fought. However, in so doing, he often shifts focus from the physical terrain itself to the effects of those conditions on different psychological “grounds.” Sun Tzu explains that the nature of terrain may be classified as one—or a combination—of six distinctive types. These types are: “accessible, entrapping, indecisive, constricted, precipitous, and distant.” After he and his commentators have explained how to deal with each of these by way of either engaging or not engaging the enemy, they turn their attention to disasters that cannot be blamed on natural surroundings but instead on faulty leadership.

The dangers inherent in a general’s weakness or indecision has just as much influence on the readiness of troops to fight as the conditions of the terrain on which a battle takes place. This holds true of all subcommanders and officers relative to the units they command. The link must be as strong on one side as it is on the other, because even a “valiant” officer cannot make up for a poorly trained unit, and a well-trained unit cannot overcome poor leadership. Sun Tzu says, “When the general is morally weak and his discipline not strict … when the formations are slovenly the army is in disorder.” It is therefore up to the general to catch and correct problems within the ranks. This will ensure the entire “body” of his fighting force has the same goals and consistency of discipline.

Sun Tzu and his commentators then turn to the process of choosing elite troops for special operations that require efficiency, speed, and a “vanguard sharp point.” Ho Yen-hsi lists titles for the different types of elite troop actions, including the “Leapers and Agitators” of the T’ang forces.

The chapter concludes with six conditions a general must remain vigilant against, as they are signs of defeat. The first two of these have to do with the physical terrain on which a battle is fought and the capacity of the commander to estimate the situation relative to both his own and his opponent’s forces. Discussion then turns to the metaphoric “terrain” of the army structure, starting with the right of the general to disobey a sovereign’s orders for the good of the state. The point is made that the decorum of the commander sets the tone for everyone else, and several examples are given of generals who shared hardship with their men, and were neither too strict nor too indulgent: “He treats them as his own beloved sons and they will die with him.”

Chapter 11: The Nine Varieties of Ground

Sun Tzu and his commentators quickly run through descriptions of nine different varieties of ground on which a battle may take place, ranging from the easiest to the most desperate, with tactics on how to handle each. The first three are “dispersive” (within one’s own territory), “frontier” (making a shallow penetration into enemy land), and “key” (neutral, or mutually advantageous). Sun Tzu recommends not engaging the enemy on these varieties of ground because little can be gained by doing so. However, on “communicating” ground (which is expanded and level to accommodate fortifications), a worthwhile engagement with the enemy can be conducted only if the general sees to it his formations remain together.

“Focal” ground—that which is surrounded by three other states—offers an opportunity to gain allies. Sun Tzu warns that this approach requires careful preparation ahead of time and involves a risk that allies may be undependable. The “serious” type of ground is one in which deep incursion is made into enemy territory. While this type of ground offers opportunity for plunder, it is also “ground difficult to return from.” When in difficult ground, it is best not to linger because this is a terrain of mountains, cliffs, swamps, and fast-running rivers that slow down and expose troops to ambush and traps. An “encircled” ground is one in which troops are pressed both by opposing forces and rough terrain, and the best way out of it is to “devise stratagems.” The ninth classification of ground is “death,” meaning the army may survive only by fighting out of desperation.

Following this identification and description of the nine varieties of ground, Sun Tzu and his commentators weigh in on specific elements that must be taken into account. For example, when in serious ground, a wise general “ensures a continuous flow of provisions.” The example of being in death ground is, by implication, the most severe test of an army’s internal discipline and order, something that must be solidly forged ahead of time. A general must be sure his troops will “fight to the death when there is no alternative, and when desperate to follow commands implicitly.”

Sun Tzu and his commentators turn their attention to various means by which deception and division can be made to frustrate the enemy’s preparations. It is worthwhile to split strong sections of the enemy off from its weaker ones, or to be “seen in the west and march out of the east.” Sun Tzu says a general must take care of his troops. He must see to it that they are well fed, rested, and disciplined (by both action and the example of staunch self-discipline), and that they trust the general’s “unfathomable plans” invariably support the greater good. It is only with this kind of strength in a fatherly type of relationship that troops will give their all in battle, even in a “death ground” situation.

Sun Tzu then states that the “Hegemonic King”—one who “snatches the position of authority”—doesn’t forge alliances with other states. Instead, he inhibits the ability of the enemy to do so, while keeping would-be allies at arm’s length. The reason for this is that a general who aims to dominate must demonstrate from the start that he is the only authority, and will not compromise this position by sharing authority with anyone else. For one thing, the risk of the enemy obtaining intelligence from an unreliable ally are minimized. Such plans are to be shared with no one else, thereby ensuring the enemy is unaware of when an action is a deceptive illusion or the real thing.

Chapter 12: Attack by Fire

This very short chapter is one in which Sun Tzu and his commentators briefly describe “five methods of attacking with fire.” These methods depend on weather conditions, humidity, and the direction and strength of winds. They advise that all sorts of equipment for this kind of attack should be carefully planned out and arranged well ahead of time, so that adjustments can be made to accommodate fluctuating conditions. If, for example, fire-lit missiles strike the enemy encampment, it is recommended to observe their response before following up with an attack. If the fire throws the enemy into confusion, an attack is encouraged. However, if the enemy remains calm, the wisest course of action is to wait.

Chapter 13: Employment of Secret Agents

This final chapter of The Art of War requires more than the usual commentary to understand Sun Tzu’s meanings. Sun Tzu begins with a discussion of the costs of waging war, claiming that “an army of one hundred thousand … will amount to a thousand pieces of gold daily.” He then turns his attention to the importance of foreknowledge to a prince and a general. Valuable foreknowledge of a potential enemy that may seem to the ordinary person to have come from supernatural sources can, according to Sun Tzu, be obtained by employing five different kinds of secret agents. These agents can work together as the “Divine Skein,” giving a sovereign an advantage over his enemy.

“Native” agents are those from the enemy’s country, while “inside” agents are those already inside the opposing army’s structure. With these two kinds of agents, it is important, as Tu Mu points out, to seek out anyone who has been slighted, underpaid, or mistreated, or is simply greedy or ambitious. Anyone nursing a grudge may be susceptible to flattery, generous bribery, or persuasion by an emotional or logical appeal. Such agents can pass on significant information, while simultaneously working to “create cleavages between the sovereign and his ministers.”

“Doubled” agents are spies the enemy has sent who can be bribed, then used to covey false information back to the enemy. However, as commentator Li Ch’uan points out, these kinds of agents must be handled with great care and caution. A thorough knowledge of the kind of person a doubled agent is will indicate the type of enticement to which he will most likely be susceptible. On the other end of the spectrum, “expendable” agents are those entrusted to feed the enemy leaked information that is deliberately false. Such agents are expendable because if caught in the deception, they will be killed. “Living” agents, on the other hand, are those who return with intelligence for the general’s ears only. This information can be used to gain an advantage over the enemy. This is what Tu Mu calls “‘mouth to ear’ matters.” This in itself is perilous, because if a living spy has been compromised, premature notice of secret plans might be leaked out, in which case such an agent—and anyone else to whom he may have spoken—should be killed immediately. Tu Mu follows up on this by describing the kinds of details a good and well-rewarded spy can provide the attentive general. Chia Lin sums up the business of spies and their essential worth to a state at war by saying, “An army without secret agents is exactly like a man without eyes and ears.”