Ancient Roman Military
Rome was a militarized state whose history was often closely entwined with its military history over the 1229 years that the Roman state existed. The core of the military history of the Roman Empire is the account of its great land battles, from the conquest of Italy to its final battles against the Huns.
Roman Army
History and Evolution
"Roman Army" is the name given by English-speakers to the soldiers and other military forces who served the Roman Kingdom, the Roman Republic and later the Roman Empire. The Roman words for the military in general were based on the word for one soldier, miles. The army in general was the militia, and a commander of military operations, militiae magister. In the republic, a general might be called imperator, "commander" (as in Caesar imperator), but under the empire, that term became reserved for the highest office.
The Romans only called themselves "Roman" in very formal circumstances, such as senatus populusque Romanus (SPQR), "the Roman senate and people" or when they needed to distinguish themselves from others, as in civis Romanus, "Roman citizen." Otherwise, they used less formal and egocentric terms, such as mare nostrum, "our sea" (the Mediterranean) or nostri, "our men." The state was res publica, "the public thing", and parallel to it was res militaris, "the military thing", which could have a number of connotations.
Miles has no clear etymology. We know that Rome was originally an Etruscan city, Ruma, and the Etruscans were a war-like people. Many of the early families of Rome, including some of the most aristocratic families, were originally Etruscan. It would be surprising, then, if miles had an Indo-european etymology. We don't know enough Etruscan to rule it in or out as Etruscan.
The Army came to dominate much of the land surrounding the Mediterranean Sea, including the province of Britannia and Asia Minor at the Empire's height. Little is known of the army under the monarchy. Even before the monarchy was overthrown, the army became a citizen army. It was notoriously inept. It became a professional army, with professional generals, along Greek lines in the long struggle with the Carthaginians. It became a superior army following the reforms of Gaius Marius around 100 BC.
The army ended on a note less musical. Rome became what we would call a military dictatorship. The army began to play a part in selecting emperors, removing them typically by assassination. Imperator became a very risky office to hold. At last the senate refused to nominate any more candidates and left the selection totally up to the army, but the decision to do that did not bring stability in government. In the end the empire broke in two and then spintered into rival, warring armies. By that time there were but few Romans in the Roman army. It consisted mainly of provincial troops, due to the practice of placating enemies by letting them serve in the army, which exerted military discipline over them.
Pre-Republican military evolution
Rome was probably founded as a compromise between Etruscan residents of the area and Italic tribes nearby. The kings were Etruscan. Their language was still spoken by noble families in the early empire, although sources tell us it was dying out. Under the first king, Romulus, society consisted of gentes, or clans, arranged in 80 curiae and three tribes. From them were selected 8000 pedites (infantry) and 800 celeres (cavalry) of gentes-connected men. The decimal scheme seems already to have been in existence: one unit of fast troops for every 10 of foot.At first, under the Etruscan Kings, the massive Greek phalanx was the most desired battle formation. Early Roman soldiers hence must have looked much like Greek hoplites.
A key moment in Roman history was the introduction of the census (the counting of the people) under Servius Tullius. He had found that the aristocratic organization now did not provide enough men for defense against the hill tribes (Samnites and others). Consequently, he accepted non-aristocrats into the state and reorganized society on the basis of wealth, determined at the census.Citizens were graded into six classes by property assessment. From them were recruited milites according to the equipment they could afford and the needs of the state.
From the wealthiest classes were recruited the heavy-armed infantry, equipped like the Greek hoplite warrior with helmet, round shield (clipeus), greaves and breastplate, all of bronze, and carrying a spear (hasta) and sword (not the gladius). In battle they followed the principle of "two forward, one back." The first and second acies, or lines of battle (principes, hastati), were forward; the triarii, or "third rank" (containing the veterani. or "old ones") was held in reserve. From the name, hastati, we can deduce that the hasta, a thrusting spear, was the weapon of choice. Triariis were equipped with a long spear, or pike, a shield and heavy armor.
The remaining class or classes (rorarii) were light-armed with the javelin (verutum). They were no doubt used for skirmishing, which provided some disruption of enemy ranks before the main event. The officers as well as the cavalry were either not in the six classes but were drawn from citizens who were enrolled as patricians of senatorial rank or equestrians (equites),also known as knights,they were of the first class. These were the aristocrats. Cavalry remained an aristocratic arm up to the introduction of motorized warfare.
All in all the Roman army consisted of 18 centuries of equites, 82 centuries of the first class (of which 2 centuries were engineers), 20 centuries each of the second, third and fourth classes and 32 centuries of the fifth class (of which 2 centuries were trumpeters).
Even these measures were inadequate to the challenges Rome was to face. They went to war with the Hernici, Volsci and Latini (Italics) undertook the reduction of Etruria and endured an invasion of Gauls under Brennus. Into the gap stepped one of the great generals Rome seemed able to produce at critical moments: Lucius Furius Camillus. He held various offices, such as interrex and dictator, but was never king himself.In the early fourth century BC Rome received its greatest humiliation, as the Gauls under Brennus sacked Rome itself.
The Romans wanted to abandon the city and resettle at Veii (an Etruscan city), but Camillus prevented it. If Rome was to re-establish her authority over central Italy, and be prepared to meet any similar disasters in future, some reorganization was needed. These changes were traditionally believed to have been the work of Camillus, but in another theory they were introduced gradually during the second half of the fourth century BC.Italy was not governed by city states like Greece, where armies met on large plains, deemed suitable by both sides, to reach a decision. Far more it was a collection of hill tribes using the difficult terrain to their advantage. Something altogether more flexible was needed to combat such foes than the unwieldy, slow-moving phalanx.
Undoubtedly the most important change was the abandonment of the use of the Greek phalanx. The legio, or "levy", was introduced at this time, with a structure of manipuli ("handsful"). A heavier shield, the scutum, took the place of the clipeus, and a heavier throwing spear, the pilum, was introduced. The line of battle was more open so that a rank could hurl a volley, preferably downhill, breaking the ranks of the enemy.
The first two lines carried pila. The rear rank, remaining in close order, and armed with hastae, were the pilani (not from pilum but from pilus, "closed rank"), in front of which were the antepilani carrying pila. In addition to these changes, the men began to receive pay, making a professional army possible.
The Republican Army
The historian, Polybius, gives us a clear picture of the republican army at what is arguably its height in 160 BC. Serving in the army was part of civic duty in Rome. To serve in the infantry, one had to meet a property requirement.
The Draft
The highest officers of the military were the two consuls, who were also the leading members of the executive branch of the government. Each of them ordinarily commanded an army group of two legions, which they also had the responsibility of raising. In the war-like state Rome was, the highest civilian officers were also the military chiefs of staff and the commanding generals in battle. They answered only to the senate.
Raising the legions was an annual affair. The term of service was one year, although many no doubt were picked year after year. The magistrates decided who in the tribes were to be presented for selection.The word we translate as "magistrate" was a tribal official, named, of course, a tribunus ("of the tribus"). Here a basic division of the military and civilian branches applied, as well as the subjection of the military to the civilian. The working organizations of the tribe were called comitia (the committee). They elected tribuni plebis, "tribunes of the people" as well as 24 tribuni militares, 6 per legion, who were careerists of at least 5 or 6 years service. A career would include both military and civilian offices. The 6 military tribunes were to be the senior staff of the legion.
On selection day, the presiding tribune sent the men of the tribe before the military tribunes in groups of four. The four senior staffs of the future legions oberved a priority of selection, which rotated. Each staff would take its pick, man by man, until 4200 men each had been selected, the complements of four legions. The selection of 16400 men must have taken several days, unless you imagine a very fast walk-through. Such a method begs us to suppose that arrangements had been negotiated in advance.If the circumstances of the state required it, the complement could be expanded to more men, or the consuls could draft as many as 4 legions each.
Additional forces could be drafted under ad hoc commanders termed proconsules, who served "in place of consuls." In the later republic, the relatively small number of legions commanded by the consuls (2-4) resulted in their power being overshadowed by the proconsuls, the provincial governors. They would often have more loyalty (see Marian Reforms) from their troops than their consular counterparts, and the same time have the ability to raise vast numbers of troops.
While the provincial armies were technically supposed to stay within the province their governor controlled, this was ignored by the middle of the 1st Century BC. By the end of the Republic, the various men involved in the civil wars had raised the number of legions throughout the Republic's provinces to more than fifty, many at the command of a single man.
The necessity to raise legions in a hurry, to offset battle losses, caused an abbreviation of the recruitment process. The government appointed two boards of three military tribunes each, who were empowered to enter any region in Roman jurisdiction for the purpose of enlisting men. These tribunes were not elected. The experience requirement was dropped in the case of aristocratic appointees. Some were as young as 18, but this age was considered acceptable for a young aristocrat on his way up the cursus honorum, or ladder of offices.
The appointed tribunes conducted an ad hoc draft, or dilectus, to raise men. They tended to select the youngest and most capable-looking. One is almost reminded of the British press gangs, except that Roman citizens were entitled to some process, no matter how abbreviated, but the press gangs took any male off the street. If they had to, the appointed tribunes took slaves, as after the Battle of Cannae.
Soldiers who had served out their time and obtained their discharge (missio), but had voluntarily enlisted again at the invitation of the consul or other commander were called evocati.
The Standard Legion
A standard Republican legion before the reforms of Marius (the early Republic) contained about 5000 men divided into the velites, the principes, and the hastati, of 1200 men each, the triarii, of 600 men, and the equites, of 800 men. The first three types stood forward in battle; the triarii, back. The velites and the equites were used mainly for various kinds of support.
The class system of Servius Tullius had already organized society in the best way to support the military. He had, so to speak, created a store in which the officers could shop for the resources they needed. The officers themselves were elected by the civilian centuries, usually from the classici or the patricii if the latter were not included in the classici (there is some question).
Available were 80 centuries of wealthy classici, 40 of young men, ages 17 to 45, and 40 of men 45 and older. These citizens could afford whatever arms and armor the officers thought they needed. The classici could go into any branch of the legion, but generally veterans were preferred for the triarii, young men for the velites. The rest were filled out from the young 40 centuries. The older 40 were kept for emergencies, which occurred frequently. These older men were roughly equivalent to the Army Reserve in the United States.If the arms requirement was less severe, or the expensive troops were in short supply, the recruiters selected from Classes 2 through 4, which again offered either older or younger men. Class 5 were centuries of specialists: carpenters, and so on. The Romans preferred not to use Class 6 but if the need was very great they were known to recruit from slaves and the poor, who would have to be equipped by the state.
The full equipage of arms and armor were the helmet with colored crest and face protectors, breastplates or chain mail (if you could afford it), greaves, the parma (a round shield), the scutum, an oblong wrap-around of hide on a wood frame, edged with metal, with the insignia of the legion painted on, the pilum, the hasta velitaris, a light javelin of about 3 feet with a 9-inch metal head, and a short sword they borrowed from Spanish tribes, the gladius. It was both pointed for thrusting and edged for slashing.
These arms could be combined in various ways, except that one line of battle had to be armed the same way. Most typical was a line of principes armed with pila, gladii, and defended by the scuta. The hastati could be armed that way or with the hasta and parma. The velites bore the hasta velitaris and depended on running to get them away after a throw, which is why only the young were chosen for that job.
The basic unit of the army was the company-sized centuria of 60 men commanded by a centurio. He had under him two junior officers, the optiones, who each had a standard-bearer, or vexillarius. Presumably he used them at will to form two squads. In addition was a squad of 20 velites attached to the century, probably instructed ad hoc by the centurion.
Two centuries made up a manipulum of 120 men. Each line of battle contained 10 maniples, 1200 men, exept that the triarii were only 600. The legion of 4200 infantry created in this way was supported by 800 equites, or cavalry, organized in 10 turmae (squadrons) of 80 horse each, under a master of horse (magister equitatum), who took orders from the legion commander. Cavalry was used for scouting, skirmishing and various sorts of clean-up, as well as being another reserve that could be thrown into the battle. The Republic was ignorant of armies on horseback, which, coming off the steppes of Central Asia in blitzkrieg operations, were to trouble the later empire.
The Legion in Battle
Servius Tullius, most likely originally an Etruscan soldier of fortune (to whom he built temples), saw the ineptitude of the Roman army of the times and determined to remedy the situation. He was man deeply sympathetic to the ordinary Roman, for which value he paid with his life. Before that time he established the social foundations of a superior army. The army was not at first very successful, partly because it faced superior generals and partly through inexperience. Roman generals gave up trying to defeat Hannibal the Carthaginian as he ravaged Italy, and under Fabius Cunctator (the delayer) camped at a distance and watched the doings of the Carthaginians, never getting close enough to fight.
Perhaps much can be said for watching. At any rate, the army came into the hands of a family of careerists and professional soldiers, the Cornelii, a gens of the most ancient stock, patrician through and through in the best sense of the word, the first real successors to Servius. After much trial and error, suffering personal losses, they produced one of the best and most influential generals Rome ever had, Publius Cornelius Scipio. He built the Servian army into a victorious fighting machine.
Let the Carthaginians ravage Italy. Scipio took the war to Carthage, landing in North Africa with a republican army. The strategy succeeded; Hannibal was recalled at once, he came home immediately with a disrupted army and was beaten by Scipio at the Battle of Zama, 202 BC. With the tactics developed by Scipio, now entitled Africanus, and good generalship, the army at last lived up to the potential imparted to it by King Servius. Here is how the tactics worked.First the general picked his ground. The Romans now understood fairly well the importance of taking the initiative and picking your ground, with some infamous exceptions. If the terrain was not right, the army remained within its fortified camp (which was virtually unassailable) until the enemy moved on, and then followed him, waiting for an opportunity to engage.
The ideal terrain was a gently sloping hill with a stream at the bottom. The enemy would have to ford the stream and move up the slope. The film, Spartacus, recreates the ideal scene. The legion was drawn up in three lines of battle, with the turmae and the velites placed opportunistically. The hastati in front and the principes behind were stationed in a line of maniples like chess pieces, 10 per line, separated from each other. The two centuries of a maniple fought side by side. The line of principes was offset so as to cover the gaps in the hastati, and the Triarii, somewhat more thinly spread, covered the principes.
Roman formations were open. The last thing they wanted was to be crushed together and cut down without being able to use their weapons, as they had been so many times before, and as so many armies who never studied Roman warfare were to be later. Every man must by regulation be allowed one square yard in which to fight, and square yards were to be separated by gaps of three feet.Now came the moment of battle. The turmae and the bands of velites (skirmishers) made forays opportunistically, trying to disrupt the ranks of the enemy or prevent them from crossing the stream (if there was one). While they were doing this the rest of the legion advanced. At a signal, the skirmishers retired through or around Roman ranks (there probably were trumpet calls, but we know little of them).
Picking up speed, the hastati launched pila. These heavy missiles had a range of about 100 yards. On impact they drove through shields and armor both, pinning men together and disrupting the line. Just before the hastati were to close, the principes launched a second volley over their heads. The hastati now drew gladii and closed. So great was the impact, we hear from Caesar, that sometimes the men would jump up on the enemy shields to cut downward.
What happened next depended on the success of the hastati. If they were victorious, they were joined by the principes, who merged into their line to fill the gaps and make up losses. The triarii moved to the flanks to envelop the enemy. If the hastati were not victorious, they merged backward into the principes. The third line remained in reserve unless the other two failed, in which case the front two merged into the third.
Such was the attack of a Roman legion, which was nearly always successful, if it was done correctly. Later the Romans learned how to secure their flanks with ballistae and other ³cannon-like² throwing or shooting machines. The attack depended in effect on a schwerpunkt, a massing of firepower on the enemyıs front line. Whenever the legions could not set it up, they were generally massacred.
Marian Reforms
By the end of the 2nd century BC the Republican army was experiencing a severe manpower shortage. In addition to this shortage, Roman armies were now having to serve for longer periods to fight wars further away from their home. The Gracchi had attempted to resolve the former problem by redistributing public land to the lower classes, and thereby increase the number of men eligible for military service, but were killed before they could achieve this. Thus, the extremely popular Gaius Marius at the end of the 2nd century used his power to reorganize the Republican army. Firstly, while still technically illegal, he recruited men from the lower classes who did not meet the official property requirement. He also reorganized the legions into the cohort system, doing away with the manipular system. The new legions were made up of 10 cohorts, each with 6 centuries of 80 men.
The first cohort carried the new legionary standard, a silver or gold eagle called the aquila. This cohort had only 5 centuries, but each century had double the men of normal centuries. All together, each legion had approximately 4,800 men. The Marian reforms had great political fallout as well. Although the officer corps was still largely composed of Roman aristocrats, the rank-and-file troops were all lower-class men - serving in the legions became less and less of every citizen's traditional civic duty to Rome and more exclusively a means to win glory for your family as an officer. It also meant that legions were now (more or less) permanent formations, not just temporary armies deployed according to need (the Latin word 'legio' is actually their word for 'levy'). As enduring units, they were able to become more effective fighting forces; more importantly, they could now form lasting loyalties to their commanders, as the typical 1-year consul system began to break down and generals served for greater durations. This is what made the civil wars possible, and it is why scholars often cite the Marian Reforms as the beginning of the end for the Roman Republic.
The Imperial Army
During the reign of Augustus and Trajan the army became a professional one. Its core of legionaries was composed of Roman citizens who served for a minimum of twenty five years. Augustus in his reign tried to eliminate the loyalty of the legions to the generals who commanded them, forcing them to take an oath of allegiance directly to him. While the legions remained relatively loyal to Augustus during his reign, under others, especially the more corrupt emperors or those who unwisely treated the military poorly, the legions often took power into their own hands. Legions continued to move farther and farther to the outskirts of society, especially in the later periods of the empire as the majority of legionaries no longer came from Italy, and were instead born in the provinces. The loyalty the legions felt to their emperor only degraded more with time, and lead in the 2nd Century and 3rd Century to a large number of military usurpers and civil wars.
By the time of the military officer emperors that characterized the period following the Crisis of the Third Century the Roman army was just as likely to be attacking itself as an outside invader.Both the pre- and post-Marian armies were greatly assisted by auxiliary troops. A typical Roman legion was accompanied by a matching auxiliary legion. In the pre-Marian army these auxiliary troops were Italians, and often Latins, from cities near Rome.
The post-Marian army incorporated these Italian soldiers into its standard legions (as all Italians were Roman citizens after the Social War). Its auxiliary troops were made up of foreigners from provinces distant to Rome, who gained Roman citizenship after completing their twenty five years of service. This system of foreign auxiliaries allowed the post-Marian army to strengthen traditional weak points of the Roman system, such as light missile troops and cavalry, with foreign specialists, especially as the richer classes took less and less part of military affairs and the Roman army lost much of its domestic cavalry.
At the beginning of the Imperial period the number of legions was 60, which Augustus more than halved to 28, numbering at approximately 160,000 men. As more territory was conquered throughout the Imperial period, this fluctuated into the mid-thirties. At the same time, at the beginning of the Imperial period the foreign auxiliaries made up a rather small portion of the military, but continued to rise, so that by the end of the period of the Five Good Emperors they probably equalled the legionnaires in number, giving a combined total of between 300,000 and 400,000 men in the Army.
Under Augustus and Trajan, the army had become a highly efficient and thoroughly professional body, brilliantly led and staffed. To Augustus fell the difficult task of retaining much that Caesar had created, but on a permanent peace-time footing. He did so by creating a standing army, made up of 28 legions, each one consisting of roughly 6000 men. Additional to these forces there was a similar number of auxiliary troops. Augustus also reformed the length of time a soldier served, increasing it from six to twenty years (16 years full service, 4 years on lighter duties).
The standard of a legion, the so-called aquila (eagle) was the very symbol of the unit's honor. The aquilifer was the man who carried the standard, he was almost as high in rank as a centurion. It was this elevated and honourable position which also made him the soldiers' treasurer in charge of the pay chest.
A legion on the march relied completely on its own resources for weeks. In addition to his weapons and armour, each man carried a marching pack that included a cooking pot, some rations, clothes and any personal possessions. Furthermore, to make camp each night every man carried tools for digging as well as two stakes for a palisade. Weighed down by such burdens it is little wonder that the soldiers were nicknamed 'Marius' Mules'.
There has over time been much debate regarding how much weight a legionary actually had to carry. Now, 30 kg (ca. 66 lbs) is generally considered the upper limit for an infantryman in modern day armies. Calculations have been made which, including the entire equipment and the 16 day's worth of rations, brings the weight to over 41 kg (ca. 93 lbs). And this estimate is made using the lightest possible weights for each item, it suggest the actual weight would have been even higher. This suggests that the sixteen days rations were not carried by the legionaries. the rations referred to in the old records might well have been a sixteen days ration of hard tack (buccellatum), usually used to supplement the daily corn ration (frumentum).
By using it as an iron ration, it might have sustained a soldier for about three days. The weight of the buccellatum is estimated to have been about 3 kg, which, given that the corn rations would add more than 11 kg, means that without the corn, the soldier would have carried around 30 kg (66 lbs), pretty much the same weight as today's soldiers.
The necessity for a legion to undertake quite specialised tasks such as bridge building or engineering siege machines, required there to be specialists among their numbers. These men were known as the immunes, 'excused from regular duties'. Among them would be medical staff, surveyors, carpenters, veterinaries, hunters, armourers - even soothsayers and priests. When the legion was on the march, the chief duty of the surveyors would be to go ahead of the army, perhaps with a cavalry detachment, and to seek out the best place for the night's camp. In the forts along the empire's frontiers other non-combatant men could be found.
For an entire bureaucracy was necessary to keep the army running. So scribes and supervisors, in charge of army pay, supplies and customs. Also there would be military police present.As a unit, a legion was made up of ten cohorts, each of which was further divided into six centuries of eighty men, commanded by a centurion. The commander of the legion, the legatus, usually held his command for three or four years, usually as a preparation for a later term as provincial governor.
The legatus, also referred to as general in much of modern literature, was surrounded by a staff of six officers. These were the military tribunes, who - if deemed capable by the legatus - might indeed command an entire section of a legion in battle. The tribunes, too, were political positions rather than purely military, the tribunus laticlavius being destined for the senate.
Another man, who could be deemed part of the general's staff, was the centurio primus pilus. This was the most senior of all the centurions, commanding the first century of the first cohort, and therefore the man of the legion, when it was in the field, with the greatest experience (in Latin, "primus pilus" means "first javelin", as the primus pilus was allowed to hurl the first javelin in battle). The primus pilus also oversaw the everyday running of the forces.
Together with non-combatants attached to the army, a legion would count around 6000 men. The 120 horsemen attached to each legion were used as scouts and dispatch riders. They were ranked with staff and other non-combatants and allocated to specific centuries, rather than belonging to a squadron of their own.
The senior professional soldiers in the legion was likely to be the camp prefect, praefectus castrorum. He was usually a man of some thirty years service, and was responsible for organization, training, and equipment.Centurions, when it came to marching, had one considerable privilege over their men. Whereas the soldiers moved on foot, they rode on horseback.
Another significant power they possessed was that of beating their soldiers. For this they would carry a staff, perhaps two or three foot long. Apart from his distinctive armour, this staff was one of the means by which one could recognise a centurion. One of the remarkable features of centurions is the way in which they were posted from legion to legion and province to province. It appears they were not only highly sought after men, but the army was willing to transport them over considerable distances to reach a new assignment.
The most remarkable aspect of the centurionate though must be that they were not normally discharged but died in service. Thus, to a centurion the army was truly his life. Each centurion had an optio, so called because originally he was nominated by the centurion. The optiones ranked with the standard bearers as principales receiving double the pay of an ordinary soldier.
The title optio ad spem ordinis was given to an optio who had been accepted for promotion to the centurionate, but who was waiting for a vacancy. Another officer in the century was the tesserarius, who was mainly responsible for small sentry pickets and fatigue parties, and so had to receive and pass on the watchword of the day. Finally there was the custos armorum who was in charge of the weapons and equipment.
Battle Order
Front Line 5th Cohort 4th Cohort 3rd Cohort 2nd Cohort 1st Cohort
Second Line 10th Cohort 9th Cohort 8th Cohort 7th Cohort 6th Cohort
The first cohort of any legion were its elite troops. So too the sixth cohort consisted of "the finest of the young men", the eighth contained "selected troops", the tenth cohort "good troops". The weakest cohorts were the 2nd, 4th, 7th and the 9th cohorts. It was in the 7th and 9th cohorts one would expect to find recruits in training.
The last major reform of the Imperial Army came under the reign of Diocletian in the late 3rd Century. During the instability that had marked most of that century, the army had fallen in number and lost much of its ability to effectively police and defend the empire. He quickly recruited a large number of men, increasing the number of legionnaires from between 150,000-200,000 to 350,000-400,000, effectively doubling the number in a case of quantity over quality.
Weapons and Equipment of the Army
Patterns of Roman Wars
The first Roman wars were wars of expansion and defence, aimed at protecting Rome itself from neighbouring cities and nations by defeating them in battle. This sort of warfare characterized the early Republican Period when Rome was focused on consolidating its position in Italy, and eventually conquering the peninsula. Rome first began to make war outside the Italian peninsula in the Punic wars against Carthage. These wars, starting in 264 BC saw Rome become a Mediterranean power, with territory in Sicily, North Africa, Spain, and, after the Macedonian wars, Greece.
One important point that must be understood is that the Rome did not conquer most nations outright, at least at first, but instead forced them into a submissive position as allies and client states. These allies supplied men, money, and supplies to Rome against other opponents.
It wasn't until the late Republic that the expansion of the Republic started meaning actual annexation of large amounts of territory, however in this period, civil war became an increasingly common feature. In the last century before the common era at least 12 civil wars and rebellions occurred. These were generally started by one charismatic general who refused to surrender power to the Roman Senate, which appointed generals, and so had to be opposed by an army loyal to the Senate. This pattern did not break until Octavian (later Caesar Augustus) ended it by becoming a successful challenger to the Senate's authority, and was crowned emperor.
As the emperor was a centralized authority with power focused in Rome, this gave both a benefit and weakness to expansion under the Roman Empire. Under powerful and secure emperors such as Augustus and Trajan, great territorial gains were possible, but under weaker rulers such as Nero and Domitian, weakness resulted in nothing more than usurpation. One thing that all successful emperors had to accomplish was the loyalty of the legions throughout the empire. Weak emperors such as those relied upon generals to carry out their direct actions along the border, especially considering their requirement to stay in Rome to maintain power. This meant that often expansion in the empire came in leaps and bounds rather than a slow march.
Another important point to remember is that many of the territories conquered in the imperial period were former client states of Rome whose regimes had degraded into instability, requiring armed intervention, often leading to outright annexation.
Unfortunately, the weakness of some emperors meant that these generals could wrest control of those legions away. The third century saw a crisis and a high number of civil wars similar to those that characterized the end of the Republic. Much like then, generals were wrestling control of power based upon the strength of the local legions under their command. Ironically, while it was these usurpations that lead to the break up of the Empire during that crisis, it was the strength of several frontier generals that helped reunify the empire through force of arms.
Eventually, the dynastic structure of the imperial office returned due to the centralization of loyalty and control of the military once more, and then collapsed once again for the same reasons as before, leading to the destruction of the Western Half of the Empire. At this point, Roman military history becomes Byzantine military history.
ALPHABETICAL INDEX OF ALL FILES
CRYSTALINKS MAILING LIST, NEWSLETTER, UPDATES