Vegetius on Strategy

The work of Sun Tzu was unknown to western civilization for many centuries. In its place... cherished by Charlemagne, Richard the Lion Hearted, and England’s Henry II... Vegetius. The most influential treatise on military strategy between the age of the Romans and the Clausewitz’ Napoleonic era was written by the Roman citizen Flavius Vegetius Renatus in (approx.) 390 AD. His De Re Militari contains insight into strategic planning and operations that are relevant still.

Vegetius' book was available to kings and generals for centuries

By Vegetius’ time, the great empire of Rome was in its waning days, its once mighty military descending into atrophy and decay. The days of Julius and Augustus Caesar were a vague memory, having passed four hundred years earlier. Vegetius wrote about “the ancients,” the generals and leaders of Rome who'd connived and fought centuries before his time, and sought to capture and share concepts of strategy that had put Rome civilization into its long-held position of dominance. Despite his aspiration to help restore Rome to its days of glory, Vegetius came along too late to make a difference, and he was little noticed by Romans of the time. In the centuries to come, though, his work became a staple for strategists and leaders throughout Europe.

Key among his directives was an emphasis on the strategic use of reserves. “It is better to have several bodies of reserves than to extend your front too much.” Vegetius wrote this:

“The method of having bodies of reserves in rear of the army, composed of choice infantry and cavalry, commanded by the supernumerary lieutenant generals, counts and tribunes, is very judicious and of great consequence towards the gaining of a battle. Some should be posted in rear of the wings and some near the center, to be ready to fly immediately to the assistance of any part of the line which is hard pressed, to prevent its being pierced, to supply the vacancies made therein during the action and thereby to keep up the courage of their fellow soldiers and check the impetuosity of the enemy. This was an invention of the Lacedaemonians, in which they were imitated by the Carthaginians. The Romans have since observed it, and indeed no better disposition can be found.”

Rommel understood the strategic importance of reserves. Fortunately, Hitler did not.

Rommel understood the strategic importance of reserves. Fortunately, Hitler did not.

Figure2: Rommel understood the strategic importance of reserves. Fortunately, Hitler did not.Consider the impact on history of Hitler’s refusal to keep strategic reserves available to the defense of Normandy, despite the advice of the great German general Erwin Rommel. Had the Germans simply allowed the Allies to land in Europe, then concentrated reserve forces immediately to the area, the endgame of the European theater of WWII would have brought even more agony to western civilization.

In business strategy, the concept has morphed to what we call “emergent strategy.” Strategists like Henry Mintzberg insist that over-planning leads to the investment of resources into initiatives that may not work out. Likening typical strategic planning efforts to “strategic programming,” Mintzberg suggests viewing the strategist as experimenter: Try several things, see what works, then follow-up with the deployment of reserves, in the form of reserved capital and available personnel, aimed directly at the point of weakness duly discovered.

The strategic use of reserves in many ways the essence of what strategy is all about. Once called “the art and science of options,” strategy as a domain of thought is epitomized by the notion of keeping one’s options open so that the best possible solution is available at just the right time.

Rommel and staff inspecting defenses on preparation for the inevitable D-Day invasion.

Rommel and staff inspecting defenses on preparation for the inevitable D-Day invasion.

Another key piece of counsel: Avoid unnecessary impedimenta. Impedimenta, the encumbrance of supply trains and support people and materiel, impedes the ability of an army or organization to move about the strategic space in a nimble, flexible manner. Clearly, for example, Southwest Airlines has sustained its success for decades in competition with the so-called “major” air carriers because its leaders have minimized impedimenta, while American, Delta, United and the others remain encumbered by large “hub” airports, a variety of planes and equipment requiring redundant teams of pilots and technicians, and large, entrenched, and increasingly inflexible workforces.

Donald Rumsfeld, George W. Bush’s Secretary of Defense from 2001 to 2006, famously insisted on sending a smallish, “nimble” invasion force into Iraq, heeding Vegetius’ admonishment about avoiding encumbrance. First revered for his experience, then beleaguered, and finally brought down by events in Iraq, Rumsfeld was no doubt proven right as far as the right-sizing of an invasion force. The American coalition defeated Saddam Hussein’s traditional army within weeks of the commencement of hostilities. Rumsfeld’s strategy, or lack-thereof, was laid bare, though, once Baghdad was taken and Saddam on the run. It was there that a second war commenced in the form of insurgency. A strategy of invasion against a traditional defending army and that of an occupation in the midst of insurgency are two different things. See my section on Metaphors and Frames of Mind for more on this.

Quotes from Vegetius follow:

“An army too numerous is subject to many dangers and inconveniences. Its bulk makes it slow and unwieldy in its motions; and as it is obliged to march in columns of great length, it is exposed to the risk of being continually harassed and insulted by inconsiderable parties of the enemy. The encumbrance of the baggage is an occasion of its being surprised in its passage through difficult places or over rivers. The difficulty of providing forage for such numbers of horses and other beasts is very great.”

“The ancients, taught by experience, preferred discipline to numbers.”

The Military Institutions of the Romans (de Re Militari)
By Vegetius
Buy on Amazon

The legion had a train of joiners, masons, carpenters, smiths, painters, and workmen of every kind for the construction of barracks in the winter-camps and for making or repairing the wooden towers, arms, carriages and the various sorts of machines and engines for the attack or defense of places. They had also traveling workshops in which they made shields, cuirasses, helmets, bows, arrows, javelins and offensive and defensive arms of all kinds. The ancients made it their chief care to have every thing for the service of the army within the camp. They even had a body of miners who, by working under ground and piercing the foundations of walls, according to the practice of the Beffi, penetrated into the body of a place. All these were under the direction of the officer called the prefect of the workmen.


Here are some other quotes from Vegetius’ De Re Militari. Parallels to issues facing strategists’ today, I think, are obvious.

“but they should consider that a battle is commonly decided in two or three hours, after which no further hopes are left for the worsted army. Every plan, therefore, is to be considered, every expedient tried and every method taken before matters are brought to this last extremity. Good officers decline general engagements where the danger is common, and prefer the employment of strategem and finesse to destroy the enemy as much as possible in detail and intimidate them without exposing our own forces.”

All overconfidence, as most pernicious in its consequences, must be banished from the deliberations. He must examine which has the superiority in numbers, whether his or the adversary's troops are best armed, which are in the best condition, best disciplined and most resolute in emergencies. The state of the cavalry of both armies must be inquired into, but more especially that of the infantry, for the main strength of an army consists of the latter. With respect to the cavalry, he must endeavor to find out in which are the greatest numbers of archers or of troopers armed with lances, which has the most cuirassiers and which the best horses. Lastly he must consider the field of battle and to judge whether the ground is more advantageous for him or his enemy. If strongest in cavalry, we should prefer plains and open ground; if superior in infantry, we should choose a situation full of enclosures, ditches, morasses and woods, and sometimes mountainous.

Fidelity is seldom found in troops disheartened by misfortunes.

It is essential to know the character of the enemy and of their principal officers-whether they be. rash or cautious, enterprising or timid, whether they fight on principle or from chance and whether the nations they have been engaged with were brave or cowardly.

It is necessary to know the sentiments of the soldiers on the day of an engagement. Their confidence or apprehensions are easily discovered by their looks, their words, their actions and their motions

Good generals are acutely aware that victory depends much on the nature of the field of battle. When you intend therefore to engage, endeavor to draw the chief advantage from your situation. The highest ground is reckoned the best. Weapons thrown from a height strike with greater force; and the party above their antagonists can repulse and bear them down with greater impetuosity, while they who struggle with the ascent have both the ground and the enemy to contend with. There is, however, this difference with regard to place: if you depend on your foot against the enemy's horse, you must choose a rough, unequal and mountainous situation. But if, on the contrary, you expect your cavalry to act with advantage against the enemy's infantry, your ground must indeed be higher, but plain and open, without any obstructions of woods or morasses.

Men must be sufficiently tried before they are led against the enemy.

It is better to have several bodies of reserves than to extend your front too much.

A general is not easily overcome who can form a true judgment of his own and the enemy's forces.

Troops are not to be led to battle unless confident of success.

How Wars Are Won: The 13 Rules of War from Ancient Greece to the War on Terror
By Bevin Alexander

On finding the enemy has notice of your designs, you must immediately alter your plan of operations.

Good officers never engage in general actions unless induced by opportunity or obliged by necessity.

One excellent and general rule must be observed. If you intend to engage with your right wing only, it must be composed of your best troops. And the same method must be taken with respect to the left. Or if you intend to penetrate the enemy's line, the wedges which you form for that purpose before your center, must consist of the best disciplined soldiers. Victory in general is gained by a small number of men. Therefore the wisdom of a general appears in nothing more than in such choice of disposition of his men as is most consonant with reason and service.

But the complete Roman legion [from elsewhere: a legion is usually 6,000 strong, sometimes more], in its own peculiar cohorts, contains within itself the heavy-armed foot, that is: the principes, hastati, triarii, and antefignani, the lightarmed foot, consisting of the ferentarii, archers, slingers, and balistarii, together with the legionary cavalry incorporated with it. These bodies, all actuated with the same spirit, are united inseparably in their various dispositions for forming, encamping and fighting. Thus the legion is compact and perfect in all its parts and, without any foreign assistance, has always been superior to any force that could be brought against it. The Roman greatness is a proof of the excellence of their legions, for with them they always defeated whatever numbers of the enemy they thought fit, or their circumstances gave them an opportunity to engage.

A soldier, as he advances in rank, proceeds as it were by rotation through the different degrees of the several cohorts in such a manner that one who is promoted passes from the first cohort to the tenth, and returns again regularly through all the others with a continual increase of rank and pay to the first. Thus the centurion of the primiple, after having commanded in the different ranks of every cohort, attains that great dignity in the first with infinite advantages from the whole legion. The chief praefect of the Praetorian Guards rises by the same method of rotation to that lucrative and honorable rank.

But of all precautions the most important is to keep entirely secret which way or by what route the army is to march. For the security of an expedition depends on the concealment of all motions from the enemy. The figure of the Minotaur was anciently among the legionary ensigns, signifying that this monster, according to the fable, was concealed in the most secret recesses and windings of the labyrinth, just as the designs of a general should always be impenetrable.

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