An Unstoppable Machine: 5 Steps in the Evolution of Roman Warfare

An Unstoppable Machine: 5 Steps in the Evolution of Roman Warfare

Patrick Lynch - June 7, 2017

The Roman army was unquestionably one of the most effective military forces in history. However, ancient historians disagree over the origin of the army. Plutarch claims that Romulus formed the legionary forces whereas Livy wrote that in early Rome, they fought as a kind of civil militia. Sometime in the 6th century BC, King Servius Tullius introduced wealth classes in Rome. The equites were the highest ranking citizens and formed the cavalry whereas the lowest group were not allowed enter the military.

At this stage, there were 18 centuries of equites, 82 First Class centuries, 20 Second, Third and Fourth Class centuries and 32 Fifth Class centuries. This is how Rome approached warfare at the beginning of the Republic but a humiliating defeat to the Gauls at Allia in 390 BC; when the enemy sacked Rome, led to significant changes in the way the Romans conducted military affairs. Let’s take a look at how Rome’s warfare evolved throughout the centuries.

An Unstoppable Machine: 5 Steps in the Evolution of Roman Warfare
Roman Phalanx. Business Insider

1 – The Roman Legion in the 4th Century BC

Rather than foolishly continue with the same military outline after their embarrassment against the Gauls, the Romans showed their penchant for innovation that helped it ultimately form one of the world’s great empires. The abandonment of the Greek phalanx was probably the most important change. While the phalanx worked well on open plains, the Romans often fought in tighter spaces, so they needed a more flexible formation.

In the 4th century, the average size of a Roman legion was probably 4,800 men. It consisted of three lines of soldiers. The first line included around 900 hastati that carried the scutum (rectangular shield), a sword and possibly a javelin. Approximately 300 leves were attached to the hastati; these were lightly armed men ideal for skirmishes. The second line included 900 principes; these were experienced fighters with the best equipment in the legion. The third line included 2,700 maniples which consisted of triarii (veterans), rorarii (inexperienced fighters), and accensi (considered the least reliable soldiers).

Regarding tactics, the hastati would attack first, and they had the option of falling back behind the principes and waiting for counter attacking opportunities if they encountered difficulties. The triarii were a few yards behind the second line and would charge with spears if the infantry was pushed back. Their sudden emergence would often surprise enemies and give the infantry a chance to regroup. If a battle was lost, the first and second lines could take cover behind the larger numbers of the triarii and conduct an orderly retreat.

There were some important changes to the equipment too, and Fluvius Camillus is given credit for some of them. Bronze helmets were replaced by an iron headgear with a polished surface so enemy blades would slide off them. Camillus may have introduced the scutum, the famous large rectangular shield, although it was likely the work of several men.

According to Livy, Rome had two legions in 362 BC but doubled in size by 311 BC. These innovations worked well throughout the fourth and three centuries BC as Rome defeated the Samnites, the Gauls and eventually saw off the formidable King Pyrrhus of Epirus; although this was more down to the constantly supply of fresh troops than anything else.

According to Polybius, the Romans had the best army in the Mediterranean by the outbreak of the First Punic War in 264 BC. They had 32,000 soldiers and 1,600 cavalry and could call upon another 30,000 soldiers and 2,000 cavalry from allies. As a result, Rome defeated Carthage but received a terrible shock in the latter part of the third century BC that forced them to evolve once more.

An Unstoppable Machine: 5 Steps in the Evolution of Roman Warfare
Recreation of Roman soldier throwing a pilum. Pinterest

2 – Scipio Africanus Saves Rome & Reforms the Army

Scipio was a soldier and witnessed first-hand the devastation suffered by the Roman army at the hands of Hannibal, the outstanding Carthaginian general, at Lake Trebia in 217 BC and Cannae in 216 BC. Roman losses at Cannae are still among the worst ever suffered by any army in one day in history. Despite his youth, Scipio showed exceptional leadership ability and quickly sought to change the way the Roman army operated.

He became commander of the Roman army in Spain at the age of 25 and began training his men harder than any Roman leader before him. Before his intervention, Rome relied heavily on the fighting superiority of its legionaries to win battles. Scipio knew that a continuation of this policy spelled disaster, so he studied Hannibal’s tactics and created his own movements to outfox his rival. A succession of wins, following by total victory over Hannibal at Zama in 202 BC, proved Scipio right. From that moment on, Rome would not only have brave and fearsome soldiers; they would have clever and innovate generals too.

The Roman Legion underwent a slight change during the second century BC. The hastati were still the first line of attack, but now they wore bronze breastplates or chain mail coats. Interestingly, they also had 18-inch black and purple feather plumes on their helmets to make them appear larger and thus intimidate their opponents. They carried a pilum (a wooden spear with an iron tip) and a shorter javelin than before. The new Javelin bent on impact so enemies could not use it.

The other lines now carried a long spear called a hasta instead of the pilum. The accensii and rorarii no longer existed and these men now joined the ranks of the velites. Overall, the legion was slightly more mobile, and the iron helmet was replaced by a bronze helmet made of thicker metal than the first incarnation. The cavalry force consisted of 300 men divided into groups of 30; each of which was commanded by three decuriones.

During the second century BC, the Roman army was no longer a ‘seasonal’ force; it was a full-time army due to the creation of a provincial empire. Victories at Cynoscephalae in 197 BC and Pydna in 168 BC significantly increased the amount of territory held by Rome. The result was a need for an increased army but finding the numbers proved problematic. As Rome began to conquer land in the east, wealthy citizens were intent on making, even more, money through the new trading routes. The last thing they wanted was to be called up for military service.

The days when Rome could rely upon members of the countryside to join the army were gone. Spain was the most unpopular destination for soldiers due to the large number of violent uprisings along with terrible leadership. The enlistment process was changed in 152 BC as men were chosen by lot and forced to serve for six years. Nonetheless, Rome still needed more men and started relying on allied forces. In 133 BC, Scipio Aemilianus conquered Numidia, and Iberian soldiers made up almost 70 percent of his army.

A major problem faced by Rome was the issue of competent leadership. While Scipio Africanus’ innovative tactics were adopted by generals, it was becoming increasingly difficult to find high-quality commanders towards the end of the second century BC. The wealthy classes had more opportunities to make money than ever before, and corruption plagued the flourishing republic. The Gracchi Brothers tried to change things by using land distribution to help recruit, but their murder spelled the end of that particular experiment.

An Unstoppable Machine: 5 Steps in the Evolution of Roman Warfare
Roman Legion in around 30 AD. Pinterest

3 – Gaius Marius Creates Rome’s First Professional Army

Although Marius often receives credit for performing a complete overhaul of the army, in reality, the process began decades before he finally introduced a professional fighting force to Rome. It was Gaius Gracchus, one of the Gracchi Brothers, who began the process with his Lex Militaris reform in 122 BC. It ensured that soldiers received free clothes and equipment from the state and he also reduced the military service term and installed a minimum recruitment age of 17.

By the end of the second century BC, Rome had already resorted to calling for volunteers amongst Romans who owned no property. Marius finished the job by opening the army to every Roman regardless of how poor they were; the only requirements were being fit and ready to fight. Marius changed everything because he didn’t use poor soldiers merely to plug the gaps as before, he made an entire army out of them.

In the past, conscripts resented the 6-year term, but these poor volunteers routinely signed up for much longer periods of service. At one time, fighting in the military was a duty to Rome. Now, it was a profession, a career with options and this was music to the ears of the poorest elements of Roman society. Rather than struggling to find food to eat, they became part of a collective, received decent pay and got to see parts of the world that would otherwise have remained a mystery to them.

It was a stroke of genius from Marius, and he made sure to supplement his army with experienced recruits by offering special terms to veterans. This new army saved Rome from barbarian invasions and defeated the Germans and the Cimbri. A host of other changes are attributed to Marius, but again, he probably didn’t create the reforms by himself plus he may have merely finished off other reforms.

One of the most crucial changes (supposedly made by Marius) was to alter the legion’s construction from the maniple to the cohort. He abandoned the original three lines of soldiers system and the velites. Under the new system, the army consisted of soldiers with equal weaponry and armor. It was not a brand innovation in Rome as Scipio Africanus occasionally used it when fighting the Carthaginians in the Second Punic War. An obvious reason for the change was the new recruitment method. Previously, men were chosen according to wealth, and this also dictated their place within the maniple. Now, every soldier was supposedly equal, so it made sense to provide everyone with the same equipment.

Changes were also made to the army’s weaponry. One of the iron nails on the pilum was replaced with a wooden pin so it would break on impact. Another masterstroke was to promise legionnaires gifts of land upon their retirement; it was the equivalent of a pension and seen as a reward for a long period of service to the army. When all of these reforms were complete, Rome’s army was arguably the strongest in Europe as it was resilient, flexible and vast.

On the downside, soldiers became more loyal to commanders than to Rome. Despite the new recruitment, a lot of the army was still made up of non-Romans who had no loyalty to the Republic. Their loyalties lay with their commander; if he was a charismatic, ambitious and above all, victorious, general, he usually commanded the unquestioned loyalty and respect of his men. This was a problem that came back to haunt Rome with terrible consequences.

An Unstoppable Machine: 5 Steps in the Evolution of Roman Warfare
Roman Eagle Standard. Recommended Keywords Popular Keywords

4 – An Army Fit for an Empire

Throughout the rest of the Roman Republic, successful Roman commanders paid great attention to logistics when leading an army into battle. They were also obsessed with the practice of showing outward confidence and assuredness to the men. Julius Caesar outlined how he would gather military intelligence of the enemy from any source possible including defectors and captives. Commanders usually held a war council to discuss attack strategies and utilize the experience of veterans.

By the time the Republic came to an end, and Octavian became the first Emperor of Rome, commanders preferred an aggressive full-frontal attack (after detailed reconnaissance) and successfully used terror to quell local uprisings. The Romans also readily accepted hostages and peace promises from enemies in a bid to avoid unnecessary bloodshed and perhaps gain a new ally.

Rome first engaged in naval warfare during the First Punic War and won due to its ability to continually build new vessels. Rome didn’t need a great navy in the initial stages of the Republic, and it was only in the first century BC when it began building impressive fleets again. Pompey used a powerful fleet to defeat Cicilia in 67 BC, and Agrippa used 400 ships to attack Sextus Pompeius Magnus in 36 BC. Five years later, Agrippa demolished Mark Antony and Cleopatra’s fleet at Actium. After this victory, Octavian created two fleets; the classis Misenatium at Misenium and the classis Ravennatium at Ravenna. They operated until the fourth century AD.

Under Caesar’s leadership, the Roman army was a virtually indomitable fighting machine, and Octavian had the task of trying to keep the same level of quality in a peacetime setting. Soon after Actium, Octavian created a standing army consisting of at least 28 legions of 6,000 men with a similar number of auxiliaries. In total, he had a permanent army of up to 300,000 soldiers. He increased the service period from six years to 20 years and ensured the legion’s standard (Aquila or eagle) became an important symbol of the army. In fact, the standard bearer apparently received almost as much pay as a centurion.

By the first century AD, the Roman army was equipped so that each legion could last for weeks on its own resources, an essential component of any successful invasion. Each man carried rations, a cooking pot, clothes and personal possessions along with extremely heavy armor. Best estimates suggest the soldiers carried up to 66 pounds when everything is taken into account although it could have been as high as 90 pounds.

The first century AD also saw the Romans develop better siege machines and legions were expected to engineer these machines, build bridges and a number of other specialist tasks. Clearly, there were specialists within the ranks of every legion including armorers, carpenters, physicians and hunters. One legion was normally made up of 10 cohorts of 480 men plus a few hundred horsemen. While you might think that centurions commanded 100 men, they were actually in charge of 80.

Centurions would ride on horseback while their men walked and they could also discipline the soldiers by beating them if necessary. They had a 2-3 foot long staff specifically designed for this purpose. Centurions were highly respected and sought after leaders as they often traveled around the empire where they served with different legions. Apparently, a high percentage of Centurions only left their post due to death rather than being discharged from the military. If you became a centurion, you did so with the knowledge that you were giving your life to the army.

An Unstoppable Machine: 5 Steps in the Evolution of Roman Warfare
What The Roman Cavalry Looked Like In the Late Part of the Western Empire. Rome Across Europe

5 – The Roman Military Machine Collapses, Along With the Western Empire

Rome reached its territorial peak sometime around 117 AD under the reign of Trajan, but the sheer size of the empire created challenges the Romans were unable to solve. For centuries, the Roman army focused mainly on offense with the goal being to conquer as much territory as possible. From the reign of Hadrian onwards, the onus switched to defense as the empire desperately tried to hold off the vast number of barbarians encroaching around the Danube and Euphrates.

The Romans had to establish permanent camps for this purpose, but by the middle of the third century, the army could no longer cope. The fine-tuned Roman legions became a thing of the past as cohorts were drafted in to plug the ever-increasing number of gaps in defenses. In 212 AD, Emperor Caracalla offered full Roman citizenship to all provinces and various emperors in the third century were so desperate for troops that they recruited whoever they could regardless of the source. At that time, the non-Roman members of the army were not large enough in number to trouble the legions.

During the Third Century Crisis, the power of the military came to the fore as a succession of ‘barracks’ emperors took the throne after gaining the support of an army. As a result, emperors were murdered in quick succession, and the empire was in dire straits. From the reign of Gallenius onwards (the 250s), the importance of the heavy infantry dwindled as light infantry and cavalry were preferred. In the late third century when the Crisis ended, Emperor Diocletian created a central reserve to protect the empire. While Octavian had created a huge permanent army, they were all stationed at the borders. If barbarians broke through, there were limited troop available to stop them.

Cavalry was of paramount importance in the third and fourth centuries because barbarians typically raided Roman territory instead of launching invasions. The problem with having mercenaries as soldiers came to the fore at this time. Many of the marauding barbarians had served in the Roman army and were aware of its tactics and power. The Romans tried to come up with new techniques to use cavalry to support its infantry, but they suffered a terrible defeat at the Battle of Adrianople in 378 AD. Emperor Valens’ eastern army was destroyed by powerful Gothic cavalry.

Theodosius succeeded Valens and realized that Rome could no longer rely on infantry in battle. He bribed German warlords, and by 384, he had around 40,000 horsemen in his army. The gap between the Roman military in the East and West was brutally exposed when Theodosius annihilated Magnus Maximus, the usurper, in 387. The Western army still used legionnaires, but they were no match for the mercenary horsemen in Theodosius’ army. Five years later, Theodosius once again used his horsemen to demolish an enemy.

The need for speed became apparent in the Roman infantry of the fifth century in the west and east. While the old heavy infantry survived, new units were lightly armed with maneuverability the key. An increasing number of archers were trained to combat charging cavalry. Eventually, the German federates took control of the West and Rome, and the Western Empire fell in 476. The East survived by hiring soldiers from Asia Minor to prevent German dominance of the army and it issued, even more, reforms to help the empire last almost 1,000 years longer than its Western counterpart.