Book Review: The Business of War by David Parrott

European warfare underwent a massive transformation beginning around 1500. Armies from France, Spain, and Germany descended on Italy, fighting for control of Naples, Milan, and other territories in a series of war that lasted most of the century. Not only did this lead to a revolution in tactics, but it drove a massive growth in the size of armies, fueled by a great expansion of credit in the early 16th century. The fragile states of the early modern period were unable to raise, equip, and finance these behemoth armies on their own, forcing them to turn to a wide variety of military enterprisers to meet their shortfalls.

This is the subject of David Parrott’s The Business of War: Military Enterprise and Military Revolution in Early Modern Europe. It is a revisionist look at the role mercenaries—or more broadly, military contractors—played in the evolution of European armies from feudal levies to organs of the centralized state. It challenges the conventional notion that their widespread use in the early modern period was an aberration, showing instead how they played an integral part in the evolution of both modern armies and the centralized state.

Military enterprise had always played a role on European battlefields, but the 16th century saw many innovations. Contractor-colonels extended their own resources and credit to finance the raising of regiments and drew on their personal connections to man them. Governments experimented with a variety of financing schemes as wars became more frequent and protracted, allowing them to reliably call on large numbers of troops when needed. Beyond the recruiting and equipping of regiments of combat-ready troops, monarchs also relied on military enterprise to supply provisions, ammunition, ships, and clothing. In this light, conventional assessments of early modern military contractors appear to be ex post facto judgments that ignore the actual concerns of the time. Not only were early modern bureaucracies unable to recruit much larger armies on their own, but even if they could, they would have a hard time supplying them. Contractors’ great value was their ability to tap into local markets and networks of merchants, manufacturers, and financiers that would otherwise be inaccessible.

As a competitive market, military contracting of all types was subject to market forces. The Thirty Years’ War in particular placed a huge premium on experienced troops, which saw a dramatic increase in experienced soldiers’ wages. Contracts themselves also became the object of speculation: massive Swedish and Habsburg spending fueled a run of contractor-colonels who raised regiments on their own credit, hoping to recover large profits from future conquests. This massive bubble drove the most destructive phase of the war, as commanders had to squeeze occupied territories ever more to recover their expenses; the bursting of the bubble in 1634, following the deaths of Gustavus Adolphus and Wallenstein, brought a general financial reckoning and a great reduction in army sizes.

Despite the competition for soldiers and provisions, contractors themselves were not as fickle or avaricious as often represented. Efficient delivery at reasonable cost was rewarded with continued business, giving contractors a long-term incentive to develop their relationship with a particular warlord—mercenaries were not especially mercenary. Their stake in the war effort also made them much more effective in battle than commonly credited. Indeed, if the two fundamental roles of an organization are to align incentives and coordinate action, then the nexus of state authorities coupled with private contractors was far more effective than what would otherwise be possible.

Parrott also shows how the economics of contracting had an effect on strategy itself. The more developed administrations of France and Spain preferred to negotiate large-scale supply contracts for the entire army. Centralized control and economies of scale came at the expense of flexible distribution, however, and campaigns were often restricted to besieging fortresses within the limited area of the frontier. The smaller armies of post-1634 Germany, by contrast, negotiated their own supply contracts. This made them far more responsive to local conditions, allowing commanders to undertake daring campaigns of deep maneuver that would not be seen again in Europe for at least another hundred years.

Parrott concludes with a discussion of developments after 1650. Despite the rhetoric of absolute monarchs, most states continued to use contractors for both the raising and provisioning of troops. Louis XIV’s France was the great exception, where officers were more employees of the state than proprietary stakeholders in their units. Yet even the Sun King had to contend with the dynamics that drove military enterprise in the first place. The enormous cost his wars meant that he simply could not raise the necessary capital without the buy-in of the aristocracy: consequently, the army overlooked the sale of offices from one unit commander to the next, it being the only way to incentivize commanders to invest in their units. While other states gradually adopted the French example over the 18th century, this coincided with a boom in supply and service contracts that belies the conventional narrative of centralization. In the end it was not the increasing assertiveness of monarchs, but the levée en masse of the French Revolution, that brought European armies fully under state control.

The Business of War is a fascinating book from a number of perspectives. It is a useful and much-needed addition to our understanding of state-formation in the early modern period. From a purely military perspective, it provides invaluable context for understanding warfare in the period and the constraints its commanders were under. Finally, it is a useful for understanding military contracting in general, fleshing out the problems and considerations entailed by military enterprise of any period. An extensive bibliography and notes provide a jumping-off point for further research, and an engaging style makes it accessible to specialists and casual readers alike. Highly recommended.

The Business of War: Military Enterprise and Military Revolution in Early Modern Europe by David Parrott. Cambridge, 2012.

Algorithmic Warfare, Part 1: Fighting by a Script

On 12 July 1813, representatives from Austria, Prussia, Sweden, and Russia met at Trachenberg Palace in western Poland to plan their upcoming campaign against Napoleon. The French emperor had been driven from Russia the previous winter. His reverses encouraged Sweden and Prussia to join the war on Russia’s side, and Austria was expected to join them in the autumn. Nevertheless, Napoleon remained a hreat. He had gathered reinforcements in eastern Germany and occupied a strong position over a nearly two-hundred-mile front. Fighting in the spring had shown that his genius was undiminished, and he would be a danger to any army that faced him in the field.

The allies’ campaign protocol, known as the Trachenberg Plan, was designed to mitigate this threat. The plan was simple: three armies would advance against the French from the north, east, and south. Whenever they had a local advantage, they would attack; whenever Napoleon was present, they would withdraw a short distance. The noose would draw tighter around the French position until the allies could concentrate all their forces against Napoleon himself.*

The plan worked exactly as intended. The allies advanced relentlessly, avoiding Napoleon but inflicting continual defeats on the French. The emperor fruitlessly scrambled from one side of the front to the other, but could never achieve more than minor, unsatisfying victories. By 16 October the combined allied force was able to attack his army at the Battle of Leipzig, the largest and bloodiest battle of the Napoleonic Wars. It was a crippling defeat for Napoleon that led directly to his downfall six months later.

What made the Trachenberg Plan interesting is that it was essentially an algorithm. It provided a simple, recursive set of instructions that each army could execute indefinitely until the underlying conditions changed—that is to say, until the allies were ready to fight the culminating battle. This avoided the difficulties of detailed campaign planning against an opponent so unpredictable as Napoleon. Rather than project a campaign plan weeks into the future, the allies set upon a strategy that allowed them to make reliable forward progress.

The Trachenberg Plan also avoided the command and control problems that made coalitional warfare so difficult. European powers had been fighting in continent-wide coalitions for three centuries; these often foundered on the challenges of aligning war strategies and coordinating action. The allies avoided this by establishing a single common objective and fixing the broad ways of achieving it, but otherwise allowing the separate armies complete operational independence.

The same principles that allowed the allies to defeat Napoleon appear everywhere in modern conflicts. It is most obviously in asymmetric warfare, where both insurgencies and counterinsurgencies follow strict protocols. Each relies on distributed groups of fighters acting independently, and it is the algorithms governing these groups—their rules of engagement, targets, means of attack—that define their strategies. Counterinsurgency strategies are centrally directed and aim at the reduction of violence. With insurgencies, these rules emerge organically by trial-and-error and generally last only until the defeat of a common enemy. They arrive at the algorithm sharing techniques and imitating successful groups.

Algorithmic fighting also appears in conventional warfare between more evenly matched opponents, such as the recent Nagorno-Karabakh war. Although the Azerbaijani ground campaign appeared to be traditionally planned, the air war was algorithmic. Flights of drones flew through contested airspace, where decoys baited Armenian air defenses into revealing themselves; once they did, loitering munitions struck. Any targets of opportunity identified during this time (ground vehicles, artillery, etc.) were attacked. There does not seem to have been much of a targeting plan, just a repeatable technique for the attrition of critical assets until conditions were set for the assault on Shusha which ended the war.

Azerbaijan’s asymmetric advantage—Armenia lacked loitering munitions or adequate countermeasures—was what allowed them to fight algorithmically in the first place. This gap will eventually be closed, but the proliferation of unexplored technologies creates many more such opportunities for the offense. It will be impossible for commanders to account for all the new capabilities their adversaries possess, making the battlespace too complex to manage by central direction. This mirrors the problem faced by commanders at the end of the Napoleonic period, when armies had gotten too large to manage with the slow communications of the day—the army that was better at fighting decentralized therefore held the advantage.

Part 2 will look more at the conditions that invite algorithmic warfare.

* For a good synopsis of the Trachenberg Plan, see here:

“The Art of War in Italy, 1494-1529 (A Critical Edition)”

Below is the editor’s preface to F.L. Taylor’s 1920 classic Art of War in Italy, 1494-1529, published September 2020. It describes the birth of Early Modern warfare during the Italian Wars, and is available to US readers here (international rights pending).

The Italian Wars, which opened with the roar of French cannons knocking down the medieval fortress walls and closed with well-disciplined Spanish tercios standing triumphant on the battlefield, witnessed the birth of modern European warfare. Between Charles VIII’s invasion of 1494 and the 1559 Treaty of Cateau-Cambrésis, European armies were completely transformed from cavalry-heavy feudal levies to professional forces of well-drilled infantry.

Frederick L. Taylor’s superb 1920 essay covers the first three decades of the wars, during which the bulk of these crucial changes took place. A rapid succession of large-scale battles gave generals the chance to experiment with new techniques and learn from their failures, turning Italy into the military laboratory of Europe. They employed the separate arms, old and new, in various combinations and tactical schemes, using heavy cavalry, carefully-drilled pike squares, gunpowder-armed infantry, mobile field artillery, and newly-introduced light cavalry to different effects. Fortress designs and siege techniques meanwhile evolved in mutual competition as heavy cannons proved not to be the invincible offensive weapons they first appeared.

Although different nations maintained distinct fighting styles, by 1529 it was apparent that any successful army had to be built around infantry formations combining pike and shot, with the other arms playing a supporting role. This date neatly divides the Italian Wars in half: before this time, fighting was largely confined to Italy. In the following decades, the wars expanded into much larger, continent-wide affairs that pitted massive coalitions against each other, a type of war that would dominate Europe up to the author’s day.

Frederick L. Taylor published his classic study in 1921, in the shadow of the Great War. He was born in 1892 to a middle-class family in London, where he attended Hackney Downs School before going off to St. John’s College, Cambridge. His studies were interrupted by the outbreak of war: he was recruited into the University and Public Schools Battalion of Kitchener’s New Army in September 1914 and served in France at the headquarters of the 18th UPS Royal Fusiliers.

In June 1916 Taylor returned to England to attend officer training, and was commissioned a second lieutenant in September that year. He was back at the front to command a platoon in the 17th Royal Fusiliers in the Battle of the Ancre from 13 to 18 November, the final action of the Battle of the Somme. Over the next year, he took part in the pursuit of the German Army to the Hindenburg Line and fought in the ensuing Battle of Arras. For his actions there he was awarded the Military Cross, a second-level decoration which gave him the right to suffix his name with the initials “M.C.” Taylor was wounded on fourth day of Germany’s 1918 spring offensive and returned to England, where he was discharged from the army at the rank of captain. He resumed his studies in Cambridge in the fall, spending the next several months writing his dissertation, which became The Art of War in Italy.

Taylor’s experience of the war was in some ways the culmination of the evolution he describes in Italy. The introduction of machine guns and modern artillery made warfare resemble something like siege warfare in the Renaissance. For all that Charles VIII’s cannons convinced some observers (such as Machiavelli) that castles were obsolete, rapid innovation brought the defense back up to rough parity with the offense. Fortifications were redesigned to minimize the impact of cannonballs and maximize the effectiveness of their own artillery, funneling assaulting infantry into deadly fire sacks. In response, siegecraft quickly developed into a deliberate and systematic process that guaranteed success to the attacking general, so long as he could keep his army in the field and pay the cost. Trenches were dug to provide a covered approach, the walls were breached by bombardment or explosive mines, then artillery fire covered the final infantry assault; only relieving armies, enemy harassment of supply lines, and the approach of winter made the venture uncertain.

For the next three hundred years, warfare fell into a pattern dominated by the back-and-forth of siege and defense rather than maneuver in the open field. The threat that uncaptured fortresses posed to supply lines made offensives deep into enemy territory difficult, exceptions such as Gustavus Adolphus or Napoleon notwithstanding, causing most generals to prefer a strategy of positional warfare. World War I was the logical conclusion of this pattern: hundreds of miles of fortified lines were nothing if not two massive, mutually-besieged fortresses, hopelessly blurring the distinction between siege and open-field battle. Even the particulars of the assault were similar: artillery bombardments of the defensive works followed by infantry charging out of the trenches and into the breach.

On 1 July 1916, the British detonated nineteen mines under German positions to initiate the Battle of the Somme. This explosion, the largest in history up to that point, was immediately followed by mortar fire and an infantry assault across the blast craters. The offensive made little headway in the teeth of a strong German defense, and the battle dragged out into a months-long ordeal. Taylor was not present for these early operations, but he was back at the front for the concluding phase of the battle where he fought near Beaumont-Hamel. This village was guarded by the Hawthorn Ridge Redoubt, a massive fortification which had been mined during the initial assault in July. The mine tunnel was reopened and exploded anew to commence the Battle of the Ancre on 13 November: once again the frontal assault failed to take the German redoubt, but the flanking actions, in which Taylor’s battalion participated, induced a German surrender.

Many of the details of the Battle of the Ancre reflected practices developed in 16th-century Italy. Taylor makes this connection explicit: he says of the explosive mine, an innovation of the Renaissance, that “there is little difference between the mines of Pedro Navarro and those which have recently pitted the departments of northeastern France.” In his chapter on siegecraft, he also describes how attacking forces would often make secondary breaches in fortress walls to draw defenders away from the primary one—this is effectively what the 17th RF did by their actions on the flank of the Hawthorn Ridge Redoubt.

In a more general sense too Taylor’s time mirrored the Renaissance. The increased firepower of both ages made warfare decidedly bloodier, even as generals groped for effective ways to organize their armies around the new weapons. Renaissance commanders often won decisive victories using a mixture of new and old methods, which could lead them down blind alleys—in chapter 4, Taylor notes how the magnificent victory won by French cavalry at Marignano encouraged Francis I to disastrously over-rely on them.

To the extent that The Art of War in Italy reveals the author’s thoughts on his own time, Taylor resembles his subjects by grasping the fundamental problem of his own age without necessarily seeing the way ahead. In chapter 6 he states: “To a modern commander a relentless hunting of a retreating enemy is the one excuse for overtaxing the strength of his own men.” He may well have been thinking of his experience during the pursuit of the German army to the Hindenburg Line in February 1917, in which the British slogged through winter conditions on bad roads, struggling to maintain contact with the enemy. Despite these heroic efforts, the Germans managed to retrench in good order and the deadlock was renewed. The great challenge of the Western Front was in effectively pursuing the enemy—exploiting breakthroughs in the enemy lines was far more difficult than the breakthrough itself, however bloody that might be. The exponential growth in firepower brought a corresponding growth in logistical demands, and armies supplied by carts and horses were slowed to a crawl when they moved past their railheads. This problem could only be solved with trucks and tanks, which only appeared at the end of the war in a limited, tactical capacity.

It is interesting, then, that Taylor saw the style of warfare born in the Renaissance as fundamentally similar to that of his own day—he says of Gonzalvo de Cordoba, for example, that his operations “bear the stamp of sound modern strategy”, setting the standard for the emerging style of warfare. Any discussion of the Renaissance is liable to exaggerate its break with the past, and it is tempting to read a simplistic scheme of “medieval” and “modern” warfare in The Art of War in Italy. He does occasionally oversimplify the former, following the errors of Charles Oman’s monumental but dated The Art of War in the Middle Ages—for instance when he claims that earlier armies did not use reserves and lacked any finer level of tactical control.

Elsewhere, however, Taylor is much more sensitive to both the continuities and the genuine breaks with the past. He rightly emphasizes the continued preponderance of heavy cavalry well into the Italian Wars, and shows how it was only the massed fire of trained arquebusiers that truly displaced them, mythology surrounding the English longbow or Swiss pike notwithstanding. The Swiss, he demonstrates, revolutionized warfare not with their pike formations per se, but by developing rigorous close-order drill. The discipline that this brought to the infantry as a whole allowed the effective employment of handheld gunpowder weapons in coordination with the other arms, exemplified by the Spanish tercio. Against this, French superiority in the defining arms of both the Middle Ages (heavy cavalry) and the Renaissance (artillery) was insufficient to win lasting victory. The deciding factor of the period was not technology or even great skill in individual arms, but the intelligent combination of all arms.

This increasing complexity of war demanded in turn the institutionalization of military knowledge, which was aided by another fortuitous development: the intellectual ferment of the Renaissance. Men such as Guicciardini, Machiavelli, and Giovio were both curious observers and active participants in the affairs of their time, and played important roles in the events they describe. If the Renaissance was both the revival of classical scholarship and the birth of something entirely new, however, the changes in warfare leaned decidedly toward the latter. Tactics and formations were improved by the rigor of battlefield trial-and-error, not the airy theorizing of a Machiavelli. For all that the humanists compared Swiss pike battalions to the Macedonian phalanx or drew comparisons between ancient battles and contemporary ones, their true value was in documenting the changes of their time for a wide audience. The Art of War in Italy gives us a view not just of Renaissance warfare as it was, but as it was seen at the time, myths and misperceptions included.

F.L. Taylor’s book remains, a century after it was written, one of the best single-volume surveys of the birth of early modern warfare. It is accessible to the layman and interesting to the professional, while being useful to specialists in adjacent fields. The Italian Wars had such a profound effect on the course of European history that many disciplines can profit from understanding them. For the student of medieval warfare, they put late medieval infantry developments in proper perspective, showing by way of contrast the continued relative importance of the cavalry. They are important for the political scientist too: just as pike-and-shot formations dominated European battlefields for the following century and a half, the Italian Wars brought about an international order that lasted just as long. Spanish victories led to Habsburg domination of the continent and encirclement of France until the reign of Louis XIV. Finally, these events provided the grand backdrop to the Italian Renaissance itself. The study of the Italian Wars helps us understand the humanists and the political machinations they wrote about, the princes who financed artists and armies, and the sack of Rome which brought the High Renaissance to a close.

As important as The Art of War in Italy was, Taylor himself had enough of both war and the academy. Just months after submitting his dissertation, he became a novice at St. Augustine’s Abbey at Ramsgate, taking the monastic name Adrian. He would spend the rest of his life there, becoming headmaster of the abbey school in 1924 and abbot a decade later. Dom Adrian Taylor died in 1961.

I wish to thank Tom Bekers for his help with this edition. He is a relative of Taylor’s, and generously provided invaluable details on his life and wartime experience drawn from family records and archival research. He is currently working on a biography of Taylor.

You can purchase The Art of War in Italy by clicking below:

Art of War in Italy

Byzantium’s Eastern Frontier: The Most Sophisticated Defensive System of the Middle Ages

Below is the transcript for the History Network Podcast episode “Byzantium’s Eastern Frontier”. You can listen to it here, or on iTunes or Spotify. The episode was based on this Twitter thread.

The Byzantines, the subjects of the Eastern Roman Empire, were great survivors. They outlasted their cousins in the west by a thousand years, withstanding the great waves of barbarian invasions and even managing to flourish amidst the chaos. Less than a century after the last western emperor was deposed in 476, the Eastern Romans under Justinian reconquered Italy and North Africa, and seemed on their way to restoring the entire Mediterranean to Roman rule.

Yet much of this early good fortune was illusory. More calamities were in store: plague, new waves of invaders, and economic collapse wiped away much of their gains and undermined the foundations of their rule. Amidst this fresh crop of disasters, one challenge above all else threatened to bring down the empire: the rise of Islam.

The great Arab conquests began in earnest in 633, just a year after the death of Mohammad. Muslim armies exploded out of the Arabian Peninsula, and in a few short years overran most of the Roman east: Syria, Palestine, Egypt, and Mesopotamia. Soon they were pressing into Asia Minor, sacking cities, pillaging the countryside, and occupying territory.

While this was unfolding in the east, there was ongoing trouble in the west. Nomads from the steppes crossed the Danube and raided the Balkans, establishing their own states on Byzantine territories. Slavic invaders began settling in parts of Greece and the western Balkans. The empire was collapsing on all sides.

Byzantine fortunes reached their nadir during the great siege of Constantinople of 717. That year, an Arab fleet appeared before the city and discharged an enormous army which began a year-long siege of the Byzantine capital. The city was only saved by its magnificent fortifications, which allowed it to hold out until the attackers ran out of supplies.

After these dark days of the 7th and 8th centuries, Byzantine fortunes began to turn. The empire underwent a cultural and military revival over the next 300 years that brought it to a new zenith. By the 1040s, the borders of the empire encompassed modern Turkey, Greece, and all of the Balkans, plus parts of southern Italy.

How did they manage this? The challenge was much more daunting than their earlier recovery under Justinian, as they were starting from a much weaker position. They had far less territory at the outset, and their enemies were comparatively much stronger—in the Balkans, the Bulgarians had set up a powerful kingdom on their doorstep, and in the east, the Islamic Caliphate was a large, powerful empire that also had mastery of the seas.

By the same measure, the Byzantines still held several advantages. The heartland of their empire—western Asia Minor and Thrace—were fertile and populous, giving them enough wealth and manpower to keep up the fight.

They also had a magnificently situated capital. Constantinople was both highly defensible and well positioned for commerce, profiting from the trade routes that crossed the Mediterranean and came overland from Asia.

Finally, the empire’s population by this point was very homogenous, consisting almost entirely of Greek-speaking Orthodox Christians. This gave it the cohesion and morale to hold together in even the direst of circumstances.

Following the siege of Constantinople, the frontier between Byzantium and the Caliphate stabilized in a zone along the Taurus and Anti-Taurus Mountains. These formidable ranges in southeastern Turkey separate the highlands of Anatolia from the plains of Syria and Mesopotamia. Although much of the Arabs’ offensive spirit had been dashed against the walls of Constantinople, they continued to launch large-scale incursions into Anatolia. These forays were economically devastating and occasionally managed to seize cities and fortresses. This was dangerous—if the Arabs managed to gain a permanent foothold beyond the mountains, they might well turn their full attention back to conquest.

The Byzantines’ challenge was therefore to hold off the pressure in Asia Minor long enough to restore their economy and recover their European territories; this in turn would eventually allow them to deal with the eastern menace more permanently. This strategy required patience and foresight—it was a project of generations, not years. The fruit of this long project was the most sophisticated defensive system of the Middle Ages. The Byzantines’ eastern frontier was a complex machine, making use of fortifications, soldiers, civilians, and terrain to grind down a stronger adversary. Although it was centuries in the making, it proved resoundingly successful in the end.

Before we look at how the Byzantine frontier functioned, it is worth a brief diversion into how frontier defenses have typically been arrayed throughout history. Generally speaking, there are three basic forms of defense: linear, defense-in-depth, and mobile. Each has its own strengths and weaknesses and is best suited to particular circumstances.

The linear defense is exactly what it sounds like, a long line of forts, walls, and natural barriers—think World War I trenches, the Great Wall of China, and the Roman limes along the Rhine and Danube. Defensive forces are mostly static, stationed in fixed positions, but are often backed up by a mobile reserve that than can rush to a point of crisis.

Linear defenses have to cover the entire length of a frontier in order to work, which makes them very expensive to maintain. They are usually only employed by great superpowers such as Rome or China, or along narrow, oft-contested fronts, such as those parts of Flanders that separated French and Habsburg territories in the early modern period.

The second scheme, defense-in-depth, sacrifices the strong boundaries of a linear defense in favor of a multitude of strongpoints that stretch deep into friendly territory. It works by forcing the enemy army to march through a thicket of fortresses and other obstacles that slows him down and saps his strength until his momentum is exhausted. Every fort along the way has to be reduced, which takes time, covered, which takes manpower, or bypassed, which exposes the army to attacks from its rear. Crops would be gathered behind strong walls to force the enemy to disperse over a wide area in order to forage. Defense-in-depth was the strategy of several medieval kingdoms in Western Europe, whose landscapes were dotted with castles.

A mobile defense, in contrast to the linear and defense-in-depth, is far more flexible. The bulk of forces are kept in the field armies which march out and meet the invaders in open country. Detachments might be prepositioned in fortresses along likely invasion routes, but this was only to delay the enemy enough for the main army to assemble. This was what the Byzantines used on their western frontier. Whenever the Bulgarians or some other people invaded, the army would assemble and march out to fight them off.

A variant of the mobile defense is the elastic defense. The defending army falls back under pressure, only stopping to harass and delay the enemy. As the invasion progresses, enemy supply lines get longer while the defender’s get shorter, while also operating on friendly ground. Eventually, the advantage shifts so far to the defender that he launches a devastating counterattack, snapping back like an elastic band—exactly what the Russians did against Napoleon and Hitler.

This type of defense only works when the defender has plenty of ground to give. For countries not quite as vast as Russia, the defender can augment his mobile forces with a defense-in-depth, dissipating the enemy’s strength in preparation for the counterattack.

This last point illustrates the fact that none of these defensive schemes are pure. All three make use of both fixed positions and mobile forces, and usually provide some protection on the frontier and in the interior; what distinguishes them is a matter of emphasis. States favored one over the others based on the threat they faced and their own capabilities. Which brings us back to Byzantium’s eastern frontier. What made this unique was that it employed all three types of defense in a phased systematic manner. It was this complex and well-coordinated scheme that broke the momentum of three centuries of invasions, allowing the Byzantines to resume the offensive.

Any defense, no matter which type, has to account for geography. The centerpiece of the Byzantines’ defense was the Anatolian plateau, rugged highlands that are too desolate to supply large troop formations for any length of time. This created problems for both invaders and defenders, but gave a comparative advantage to the Arabs, whose mobile style of desert warfare was well suited to the environment. They attacked in quick-moving columns and lived off the land, moving on to the next region before local supplies were exhausted. Since the Byzantines could not maintain large numbers of troops in a single area, they could not easily bring the enemy to battle: by the time they managed to concentrate their own field armies, the enemy had already moved on. Moreover, for much of this period they lacked the manpower to assemble sufficient forces in the first place.

Which raised another problem. Although the Arab columns were not especially large by the standards of conventional warfare—usually just a few thousand men—they were positively massive for a raiding force. Since these excursions were opportunistic by their very nature, the great worry was that they would catch a town unprepared and decide to hold onto it, incrementally expanding their territory year by year. Worse, they might surprise the Byzantines by launching a much larger expedition than usual to deliberately target a major city near the border. It was therefore critical not just to head these incursions off, but to stop them altogether if possible. Through long, bitter experience and much trial-and-error, they gradually worked out a winning strategy.

Arab raiding expeditions usually assembled in northern Syria around late August or September. This was just before the harvest in Anatolia, when the summer heat was starting to break—ideal marauding season. Fighting men gathered from all over the Islamic world, from as far as Egypt and Persia, drawn by the promise of plunder. As they assembled, the Byzantines sent scouts and spies to figure out which route the invaders would take. As soon as they found out, frontier commanders rushed infantry to block the high mountain passes along the way—a natural linear defense.

Sometimes this stopped the invasion dead in its tracks; more often, the highly mobile column just found another route. Even so, this gave the Byzantine frontier commander critical intelligence and time to assemble his forces in a suitable location. If the enemy force was not especially large, he would seek out battle immediately, a straightforward mobile defense. If it was more than he could handle, he would put the neighboring regions on alert and start gathering troops from all over. In the event of a serious invasion, he could use a system of warning beacons stretching back to Constantinople itself to summon the imperial army.

Warnings were passed to the local inhabitants as well. Frontier troops were raised from the local population, and this fostered close civil-military cooperation. Centuries of raids had forced Anatolian villagers to harden their settlements, relocating to higher ground, building walls, and developing alert systems to bring crops and livestock to safety when raiders were nearby. This made it harder for the Arabs to loot and forage, often forcing them to waste time and energy on sieges of fortresses and fortified settlements. Even when they were successful, this narrowed their advance, slowed them down, and wore them down—an organic defense-in-depth, in other words.

At a minimum, this mitigated the damage from the raids; when especially effective, it could turn them back altogether. Armies can only go so far without provisions, and men hoping for easy loot could become quickly demoralized. Although this might not sound quite like victory, it had a cumulative effect over time. Raiding parties attracted fighters more by the promise of plunder than loyalty to a particular commander, so the failure of one year’s expedition would blunt the enthusiasm for the next.

While towns and fortresses were preparing their defenses, the Byzantine field armies were mobilizing. They did not do so according to standard practice, whereby the entire army mustered in one location before marching out to meet the enemy. Especially in the early centuries, the Arabs usually outnumbered the Byzantines. The latter learned from bitter experience not to rush headlong into battle, where a single defeat could knock out the bulk of their defensive troops and expose all of Anatolia to the enemy’s depredations.

At first, these field forces would strictly shadow and observe the enemy. Like the Arabs, they were mostly cavalry and could move quickly. As additional troops streamed into the area and their strength grew, they would start to skirmish with the enemy. The Byzantines would only fight when they had a clear advantage, so they launched night attacks and ambushed isolated raiding detachments, using the terrain to their benefit wherever possible. This wore down the invaders and constrained them by their mere presence, preventing raiding detachments from ranging freely across the countryside.

Up to this point, the shadowing force was no more than an auxiliary to the defense in depth. If the Arabs became discouraged at that point and turned back home, the Byzantines could chalk it up as a victory. For much of this period, that was the best they could hope for, as they simply didn’t have the manpower to do more.

But occasionally, the Byzantines were in a position to get more aggressive. The cumulative effect of attrition, fatigue from the campaign, and the encumbrance of spoils made their enemy weaker, less enthusiastic, and slower. As the Arabs were getting worn out, the Byzantines were getting stronger, as fresh reinforcements streamed into their own ranks. At a certain point, they could transition from cautious skirmishing to seeking out full-scale battle—a classic elastic defense.

The Byzantines had every advantage by this point. They were fresh, knew the terrain, and most importantly, could choose the site of battle. If they had the opportunity presented itself, they would rush their infantry ahead of the withdrawing enemy to block the mountain passes along his line of retreat. Following behind with their cavalry, they would then smash the enemy between hammer and anvil. A successful battle would reduce the enemy’s fighting strength in the near term, and if it were decisive enough, it could deter future raids for many years to come.

So to summarize: the Byzantines used a linear defense to block the mountain passes if they could, then use a mobile defense to fight off the raiders. Failing that, they used a defense-in-depth to mitigate the damage and wear the enemy down. Finally, when able, they used an elastic defense to deal the enemy a crushing blow. This complex defensive system required coordination among multiple levels, from the emperor’s armies down to fortress garrisons and the local peasantry. This was by no means a straightforward evolution, but took much experience—and many mistakes—to get right.

The Byzantines’ chief antagonist during most of this period was the Abbasid dynasty, the rulers of the great caliphate centered on Baghdad. During times of intense conflict, the Abbasids usually had the upper hand; when they had weak rulers or were preoccupied with civil strife, the Byzantines could recover and make good their losses. Over the long run, however, the Byzantine military machine was steadily improving; their victories were becoming greater and their defeats less severe.

Abbasid power began to crumble in the later 9th century, eventually to be replaced by regional powers. In Syria, they were succeeded by the Hamdanid dynasty of Aleppo, a leaner and more aggressive state that resumed the offensive in Anatolia. By this time, however, the Byzantine frontier system had come into full maturity. The empire itself was much stronger, with tax revenues flowing into the treasury, greatly expanded borders, and a much larger army. The Byzantines were able to sustain offensives of their own, sending armies into Syria and taking back cities in the borderlands that had long been under Muslim control. They were confident enough in their defenses that, whenever news arrived of an Arab raiding party, they would send their own marauders to plunder the enemy’s undefended countryside.

A series of soldier-emperors in the later 10th century brought the war with the Hamdanids to a successful conclusion. They recovered Antioch, the great metropolis of northwestern Syria, subjected Aleppo to tributary status, and brought much of the coast under Byzantine control for a time. Henceforth Syria would no longer pose a threat to the heartland of the empire.

Yet the Byzantines also knew that fortune is fickle. Success had made their defensive methods obsolete, but it might make itself useful in the future. One emperor commissioned a manual to record these techniques in a manual entitled On Skirmishing. It is our major source for the nuts and bolts of how the Byzantine army operated on the frontier, and it fills out many gaps in the narrative histories of the period.

Unfortunately for Byzantium, these methods did not do them much good in the future. The next big threat in the east would use a different style and come from a different direction: the Turks coming through the Armenian mountains. In 1071, barely a century after the Arabs of Syria were subdued, the Seljuk confederation won a resounding victory at Manzikert. This battle, which took place in the far eastern part of modern Turkey, destroyed much of the Byzantine army and opened up all of Anatolia to Turkish conquest.

Although the empire would recover from that disaster, it never again controlled the highlands that formed the centerpiece of the frontier defenses. For the rest of Byzantium’s history, the border lay along the mountains of western Anatolian rather than the Taurus farther east. Turks of various stripes dominated the plateau itself, giving them easy access to the rich provinces of the coast. This proved a constant drain on the empire, even as new, more dangerous threats arose in the west—Normans, Pechenegs, Venetians, and a revived Bulgarian state.

Despite all this, the empire survived another four hundred years. It was too strong, too rich, and too resilient to be brought down by a single calamity, and the ensuing flurry of disasters only gradually took their toll. The empire took so long to descend from the heights of its 10th and 11th century golden age precisely because that golden age was so hard-won. Every small success was built on the one that preceded it, and the effort involved the whole of society. Byzantium’s zenith was less spectacular than some other empires, but it was far more robust than those fleeting blooms. In this sense, at least, the Byzantines’ incredible frontier system defined the essence of the empire itself.

The Battle of Cannae: What Really Happened?

Hannibal’s great victory at Cannae in 216 BC is famous as a decisive victory by double envelopment. After baiting a much larger Roman army into an attack, he trapped it between the jaws of his wings, which then encircled and annihilated the Romans.

On closer examination, this traditional account of Cannae doesn’t quite add up. How did Hannibal manage to surround such a large army in the first place? Why didn’t the Romans just roll through his entire line, and surround him? A few modern narratives hint at an explanation, but never quite spell it out.

By early 216, Hannibal had been rampaging around Italy for the past year and a half, and had inflicted a number of severe defeats on Roman armies. The general Quintus Fabius then took charge of Roman strategy, and saw some success by shadowing the Carthaginian army and attacking its foragers while refusing open battle. But the Senate grew impatient for a decisive victory that could avenge its past humiliations. It spent the winter of 217-16 raising a massive army—an unprecedented eight legions plus a roughly equal quantity of allies, numbering as much as 80,000 infantry and 6,000 cavalry in all. Against this, Hannibal had only 50,000: 40,000 infantry—Libyans brought over from Africa, some from Spain, and still more recruited from among the Celts of northern Italy—plus another 10,000 cavalry. These latter were superior to the Roman cavalry in both number and quality, consisting of sturdy Celts and Iberians, and Numidian light cavalry.

With the coming of spring, the Roman Senate gave the army strict orders to chase down the Carthaginians and bring them quickly to battle. Such a large force had to move quickly in any case just to keep so many men fed. Hannibal moved out of winter quarters and headed southeast to the rich coastal plains of Apulia. There he could find plenty of forage, and the open country was ideal ground for his cavalry.

His initial target was Cannae, a village on the right bank of the Aufidus (modern Ofranto) where the Romans had been stockpiling grain. This meant that the Romans can’t starve him out and that they would need to attack him quickly to prevent their own army from starving. After a series of initial maneuvers around the Aufidus, both armies encamp on the northern (left) bank of the river on the evening of 1 August. Early the next morning, they both cross the river and form up on the opposite bank near Cannae. Whether by accident or design, the deck is already stacked in Hannibal’s favor. The sirocco is blowing out of the southwest, a hot summer wind that blew across the Mediterranean and carries dust into the Romans’ eyes.

The two armies adopt a similar formation, with infantry in the center and cavalry on the flanks. The Roman right and Carthaginian left are both anchored on the river, while the horsemen on the opposite end guard the open flank. Hannibal places his heavier Celtic and Iberian cavalry on his left and his Numidian light cavalry on his right; in the center, he places his heavily-armed Libyans at either end and his Celts and Iberians in the center.

This last point is a real problem for Hannibal. The Roman infantry at Cannae numbers close to 70,000 (they leave 10,000 to guard the camp), meaning his own is outnumbered over 3:2. If the opposing enemy wraps around right flank, he is finished.

So he adopts an unusual solution. He places the Spanish and Celtic infantry in the center, with the heavily-armed Libyans on the flanks. He then pushes the centermost companies out in front, with the adjacent companies falling off to either side.

He then does something that almost all modern accounts miss. Rather than keep his companies in a staggered formation, he orders them to wheel outward, forming a smooth flank. This is a detail that will prove crucial to his entire battle plan.

Modern writers miss this because Livy calls the formation a “wedge”, a word commonly used to describe an echeloned formation with a reinforced center. Such terminology was not standardized, however, and he was almost certainly just referring to the shape.

Polybius, whose account of Cannae calls the formation a crescent, not a wedge, specifies that Hannibal had to thin out his line to adopt this formation. It’s a simple geometry problem: an arc between two points covers a longer distance than a straight line. If the companies simply advanced at staggered intervals, their fronts would occupy the exact same distance as a straight line; if they formed a smooth front, they would have to thin out. While they might reduce the depth of their units to extend their frontage, they also probably leave substantial intervals between companies (we will see why later).

The battle begins with skirmishing by the light infantry on both sides. It is probably at this point that the Romans condense their lines, strengthening the center.

Why do this? The answer lies in the Romans’ perception during the opening phase of the battle.

The purpose of deploying skirmishers before a battle, other than to soften the enemy line, is to screen a friendly force, preventing the enemy from observing their formation. The Carthaginians employ slingers from the Balearic Islands, who whipped small, hard stones at the enemy line, forcing them to stay hunkered down beneath their shields. This, plus the dusty wind, makes it very hard for the Romans to tell what was going on.

All the Romans can see is the Punic center bulging out towards them. They can’t tell how many ranks deep it is, and probably figure that the center is heavily reinforced to smash through their own line. That is exactly what the outnumbered Thebans did at the Battle of Leuctra in 371 BC, when they famously defeated the hitherto invincible Spartans by heavily reinforcing their left and pushing it ahead to smash the Spartan right.

While all this is going on, Hannibal sends his Celtic cavalry on the left against the Roman right. These are crowded between the infantry and the river and lack room to maneuver. The Romans are soon routed by the better and more numerous Celts, who take off in pursuit.

By the time the cavalry fight is over, the Roman line is ready to advance. The whole formation moves forward as a mass, as the cavalry at the other end—Numidians on the Carthaginian right, allied cavalry on the Roman left—skirmish inconclusively.

What the Romans are not prepared for is the shape of the Carthaginian front. As the line advances and the inner maniples start making contact with the angled line, they naturally turn inward. The deeper-than-usual columns start jostling the maniples on their outer flank.

Those outer maniples also have to speed up and swing around to maintain alignment with their neighbors—in such a situation, the entire formation marches in alignment with their neighbor that is closer to the center. As the outer maniples run to catch up, they turn in at an even sharper angle.

This starts to disorder the densely-packed formations, but also does something more important: it molds the entire Roman line into a concave crescent of their own. Not something that would happen if facing a normal echeloned front.

The Carthaginian center is surrounded by this point, but Hannibal is prepared, having placing himself at the center to lead a planned retreat. As the crescent collapses under the inexorable pressure, he ensures the entire formation reverts to a line.

In truth, this is probably complete chaos. The Celtic and Iberian infantry are taking heavy casualties from the strong Roman push, and it takes all of Hannibal’s abilities to prevent the planned withdrawal from turning into a rout. The Roman, on the other hand, are already tightly packed and are converging on a single point. Even as the Carthaginians fall back onto a straight line, the Romans are prevented from changing course by the deep formations on either side.

Not that it would make much difference if they could: they are faced with the earlier geometry problem. Whereas the thinner Carthaginian units can fall back on line without running into one another, the Romans have to cram their entire frontage into a much narrower space.

This fact is well known in the ancient world. Onasander’s Strategikos advises how to deal with a larger enemy arrayed in a concave formation: rather than march into the center, where the smaller force will get encircled, he recommends attacking the protruding flanks.

This way the smaller army can overpower the enemy flanks, but the enemy center cannot advance to help out without getting crowded together and losing formation.

This is essentially what is happening to the Romans. The centermost units, which had the most direct path and were the first to make contact with the enemy, continue to push the enemy center back.

That is when things start to go horribly wrong.

As the outer maniples converge from the wings, they start to run into the center units. They knock each other around and the men in the rear struggle just to stay upright. Without the support of these men behind them, the front ranks can’t maintain the forward pressure.

This allows the Carthaginian line to stabilize and reform. As this happens, the Libyans on the either end swing in and start attacking the Romans on their flanks.

It keeps getting worse for the Romans. A few individual units are able to maintain some cohesion and face out, but they keep getting pushed on all sides by their own men. These shocks ripples through the packed mass, disrupting lines and knocking men over. As the infantry gets squeezed tighter, the Celtic cavalry return from their pursuit of the Roman right and help the Numidians defeat the Roman left.

As the Numidians pursue, the Celts turn and attack the Romans from the rear. It is all but over now.

The rest of the day is a slaughter. Groups of several thousand men break out and escape, but most are eventually captured. Those remaining are killed to a man.

So why isn’t Cannae a victory by double envelopment?

A true envelopment uses a flank attack to disrupt the enemy formation. To do that, Hannibal would have to extend his line, and the Romans would have kept formation and smashed through his thin line. Hannibal did not win by encircling the Romans. He didn’t even win by attacking their flanks. He won by turning their army into a disordered mass. By the time the Libyans entered the fray, the battle was already won.

Far more brilliant than a mere double envelopment.

As a coda, what would have happened if Cannae didn’t go according to plan? What if the Romans didn’t draw in their center? There were probably other parts to Hannibal’s plan that went unmentioned because they never came into play—he did employ at least one additional stratagem, which consisted of sending 500 cavalry across enemy lines in false surrender; once the battle was engaged, they drew their hidden weapons and started attacking the Romans from the rear. We can guess what else he might have done.

As a first possibility, the battle might develop in a similar way, but the Romans don’t draw in their lines. The extended Roman front still wraps around the extended Carthaginian frontage and get crowded together as the crescent collapses.

Because the Roman center has less impetus, the Carthaginians conduct a more orderly withdrawal and suffer fewer cavalry. Both wings of cavalry then attack the flank and rear of the Roman left to prevent an envelopment.

As a second possibility, Hannibal might indeed be hoping for a breakthrough in the center. His Celts in the center are his fiercest warriors, and stood the best chance at piercing the line.

This would explain the rush to attack with the cavalry on the left: Hannibal needed them to punch through and attack the Roman rear at the exact point as his center. This would split the Roman line and allow them to be defeated in detail.

Whatever the case, Hannibal knew that Cannae would be a hard-fought battle. As tempting as it is to imagine him as a mastermind leading the enemy by the nose, he was in a tight spot, and in the days before had twice failed to bring the Romans to battle on more favorable ground. And all of these scenarios depend on one critical factor: the absolute superiority of his excellent cavalry.

Although it is hard to imagine a more smashing victory than Cannae, Hannibal still lost over a tenth of his army—a heavy loss when he couldn’t easily recruit more. This prevented him from marching on Rome, and ultimately lost him the war.

Which adds a final touch of irony: just thirty miles from Cannae is Asculum, where 63 years earlier Pyrrhus of Epirus won another great victory over the Romans, losing fewer men than Hannibal. This was the battle that gives us the term “pyrrhic victory”.

The above was adapted from a thread on Twitter.

DRONE APOCALYPSE: The End of Warfare As We Know It?!

The spate of impressive drone strikes over the past year has revived talk of the extinction of armored vehicles. Since late 2019, Turkish UAVs in Syria and Libya and now Azerbaijani drones in Nagorno-Karabakh have destroyed a sizable number of tanks, APCs, artillery pieces, and SAMs. Protective armor can only do so much and brings exponential costs with it; against that, swarms of drones are cheap. Is the age of armored military vehicles over?

Before we get carried away, it is worth remembering a few things. Each one of these conflicts is a propaganda war above all else, and it is not always clear what we are actually seeing. Many videos of drone strikes are clipped just after the explosion, making it impossible to assess the actual damage. Moreover, we have only seen attritive strikes on individual targets, not decisive attacks in support of a larger offensive—picking off stray vehicles is very different from collapsing a defensive line. Finally, armored vehicles have not yet in fact disappeared from any of the battlefields in question.

Advances in UAVs will gradually alter the dynamics of warfare, but it is ridiculous to suggest that they are on the cusp of completely upending things. There are three principal reasons for this: the nature of combined arms, the economics of drone warfare, and the operational difficulties of drone strikes.

The combined arms race

UAVs are no different in the essentials from any other air or missile platform. Anti-air systems have already destroyed a number of them in Syria, and there are plenty of existing ways to blunt their effectiveness: active protection systems, reactive armor, and better tactics, to name a few.

Recent strike footage, by contrast, shows 40+-year-old Soviet equipment in isolated, unentrenched, and unsupported positions. This has concentrated a lot of attention on the vulnerability of individual vehicles while ignoring how armies fight as a whole. Individual arms do not fight separately: it is unthinkable to send armor into urban environments without an infantry screen, or infantry into action without artillery support. Soon, it will be unthinkable to deploy armored vehicles unsupported by counter-UAS systems.

Pantsir-S1 firing

Modern militaries are only now beginning to field cUAS systems as part of doctrine. The Russian-built Pantsir gives us a good idea of what these will look like: a rapid-firing radar-guided cannons and missiles mounted on an armored chassis that can maneuver alongside other ground elements. Pantsirs have already successfully defended against drone swarms in Libya and Syria, adding yet another element to the thicket of modern combined arms.


It is interesting, then, that some of the highest-profile drone kills have been Pantsirs. In all cases the attacking UAV is thought to be the Israeli-produced Harop, a kamikaze drone employed by the Turks in Libya and the Israelis themselves in Syria. The Harop likely exploits specific gaps in the Pantsir’s capabilities: it is relatively fast, has a small radar cross-section, and flies directly into the top of its target (it is also possible that Assad’s and Haftar’s crews are too inexperienced). These gaps can and undoubtedly will be closed, and may not even exist with newer models—only older S1 models have been destroyed, not the S2 with an upgraded radar.

Which brings us to the race between the offense and defense. As weapons get better, both drones and cUAS systems will get more expensive. But costs rise faster in the air, as every upgrade brings new weight, balance, and power issues in addition to the cost of the improved avionics and munitions themselves. This undercuts the primary advantage of drones, which is that they are cheap and easy to manufacture.

As it is, the Harop is not especially cheap—about $10 million a piece, against $15 million for the Pantsir. As weapons evolve, militaries will face a tradeoff between low cost and higher kill probability. Their adversaries will meanwhile use anything they can to reduce the latter: decoys, radar spoofing, baited ambushes, complex defenses, etc. War is not a simple cost problem, but economics do affect inventories (more on this in a bit). Simply put, commanders will have to be discriminating in their use of drones, and will not be able to wipe out enemy ground forces at will.

What about at the lower end, where small, cheap drones can sneak past radars undetected? ISIS has used off-the-shelf drones armed with grenades for years, and new variants will get better while remaining low cost. This is an old problem, however: a short-range, small-yield explosive is no different in effect from mortar-fire. They will face many of the same difficulties of employment and limited capabilities, meaning they will hardly be groundbreaking.

The employment of UAVs

Another point of note about recent footage is that we only see the final part of the strike. We do not see the rest of the kill chain: the identification of the target, the communication of targeting data, the UAV moving to engagement range. We also do not see the enabling infrastructure: the airfields, the technicians, or the logistics of getting them in theater.

From a supply chain point of view, commanders will have to consider the number of UAVs they have on hand and how long it will take to be resupplied. The more advanced the weapon, the fewer are stockpiled—the era of precision-guided munitions raises the real possibility of running out of ammo in the opening phases of a conflict. This will force commanders to reserve drones for deliberate offenses, where they can achieve combined effects in conjunction with other forces. The old rules of warfare will still prevail, in other words.

Finally, there are major tactical vulnerabilities in the current crop of drones. Most of their recent success has come from their ability to loiter as they seek out targets or wait to be fed targeting data. The skies will not always be uncontested, however, and the longer that drones loiter the more easily they can be targeted by ground fires or counter-drone swarms.

In 1513, awed by the cannons which had recently brought down castle walls across Italy, Machiavelli argued that fortresses were obsolete. Just seven years later, in The Art of War, he detailed the kind of fortifications a prince should build—fortress design had caught up to the offensive power of cannons. So it always is in war: new weapons alter the battlefield, but the change is always far more gradual than it first appears. Drone maximalists tend to imagine buzzing drones filling the sky and vaporizing any ground forces, but don’t think through what that would entail. Just as artillery in the First World War and bombers in the Second failed to simply wipe out the enemy from afar, UAVs will take their place in modern armies as one piece of a complex, slowly-evolving system.