Since the time of Constantine the Great, the Roman Army has undergone a radical reorganization, to such an extent that it hardly resembles the old army of the years of the Augustan Empire. Then the power source of the army was the foot legionaries, armed with heavy javelins (pila), large shield, breastplate of iron plates and heavy crushing sword (gladius).
The legionaries were supplemented by the famous divisions of the Auxilia (auxiliaries, analogous, in a way, to the divisions of the Greek peltasts), the archers and the psilis. The Roman cavalry was neither numerically strong, nor was it ever distinguished for its endurance and stability.
As long as the Empire's only opponents were the various barbarian races, whose strength came from their numerous and swift infantry, the strong armour, training and discipline of their legionnaires usually ensured victory.>
From the end of the 2nd century AD however, the need for the presence of strong fast-moving forces on the Empire's frontiers was strongly demonstrated. Thus the powerful legion of 10 cohorts, which had sections of all weapons, was effectively abolished. Its divisions were divided into various regular detachments (Vexilla). The army of the Eastern Empire was fundamentally different from its counterpart in the West. The Greek tradition, even the military one, was particularly strong in the East and the Roman Army that was stationed in the region was greatly influenced.
Cavalry Vexilla usually consisted of one type of horsemen. The heavy cavalry of the Army of the East consisted of furnace-carriers and shuttered horsemen. The furnace-bearers were organized and equipped just like the late Seleucid visored horsemen. They were literally armored from head to toe, both themselves and their horses. They were armed with xyston (a long spear, 3.5 meters long) and swords. The shutters for their part were the evolution of Alexander the Great's Companions. They brought a long chain breastplate, scraper, swords and shield.
Of course, more Roman types of horsemen also survived in the East. The so-called equites carried a shield, javelins, swords and a short breastplate. The Illyrian equites, on the contrary, were light horsemen, equivalent to the Tarantine horsemen of the Hellenistic times. They were unarmored and armed with spears, shields and swords. The last type of cavalry was the equites sagittarii, which, as their name indicates, were light horse archers.
As for the infantry, it was distinguished into heavy and light. The heavy infantry, the former legionnaires, who were now called scutati, i.e. shield-bearers, had already abandoned the heavy javelin, the pilum, which they replaced with lighter javelins, which, however, achieved a greater range.
Each division of scuta was also supported by an organic division of small archers. The divisions of the Auxillia were divided into imperial divisions (Palatina) and serioguard divisions (Limitanei). All auxiliaries were now unarmored and carried the same armor as the scutatus and were also supported by organic divisions of light archers. But there were also divisions consisting exclusively of archers. The army was organized into permanent garrisons and the main army (Comitatenses).
The big change, however, occurred when Theodosius the Great took over the government of the state. He, in order to achieve peace with the barbarians, allowed them to settle in the lands of the Empire.
The Barbarian Allies and the Western Roman Army
In return they would provide military services. The barbarian fighters, organized according to their own standards, armed with their traditional weapons and commanded by their own chieftains, formed the infamous divisions of the foiderata. They were mainly Germans, but also Huns. Gradually the influence of the Phoiderata spread and the army reached, in the middle of the 5th century AD. to be Germanized. At the same time the native army was allowed to decline.
Only the Emperor Marcian saw to the reorganization of thearmy. So when Attila threatened to invade the Eastern Empire if tribute was not paid, Marcian replied that he was waiting for him with his army of men "not worse than his own".
The above also partially applies to the army of the Western Roman state. In the West, however, the barbarian invasions caused greater destruction and therefore a greater alteration of the old Roman military spirit. During the 4th century AD the Western Roman army resembled its Eastern counterpart, since both were products of the military reforms of Constantine the Great.
Gradually, however, the Roman Army itself degenerated to such an extent that at the beginning of the 4th century AD. at least half of it was made up of foiderat units. only 1/3 of Aetius' forces consisted of native soldiers. The infantry of the Western state consisted, in the 5th century AD. by small divisions of heavy infantry (legionaries), which had organic divisions of light archers and by divisions of auxiliary light infantry (auxillia), which were also supported by organic divisions of light archers. But the bulk of the infantry consisted of Frankish, Visigothic, Alanic, Burgundian and Saxon units of barbarian infantry.
The legionnaires were equipped with a chain or hardened leather breastplate, a javelin, rapiers (marzivabula), long straight swords and a large oval shield (skuta). The auxillia carried exactly the same armor, but without breastplates. The men of both types of infantry wore helmets of light construction. Smalls carried a compound bow and sword or handbook.
The Roman cavalry of the Western State was basically composed of equites, hippocontists (Illyrians) and horse archers. Aetius had very little Roman heavy cavalry and had to rely on the heavy barbarian cavalry of the Goths and other Germans. German horsemen fought in a wedge formation, armed with a lance or javelin and a large shield. A few of them, especially the leaders, wore breastplates. The only tactic they knew was the direct and impetuous attack against the enemies.
Depending on the opponent it was facing the army of the Western Empire was usually lined up with the barbarian infantry in the center, the Roman infantry in the second line in the center, the German cavalry on the right horn and the Roman cavalry on the left or vice versa. This way of formation was mainly used against other German armies.
Against the Huns, however, who had masses of light cavalry archers, he could not perform as well. The Huns, due to their speed, were able to outflank the Roman line, unless its wings rested on natural or artificial obstacles.
It was a common tactic of the Huns to quickly approach the enemy within an arrow's distance, shoot their arrows with deadly accuracy at him, and rush upon him only when he showed obvious signs of disorganization. In order to deal with the Huns, it was imperative that the Roman infantry had the ability to strike from a distance.
This was also the reason for the re-equipment of the legionnaires with lighter, longer-range javelins, as well as the subordination of small archers to each of their divisions. The barbarian infantry of the Foiderata, on the other hand, had a serious problem against the Huns. His men's javelins had a decidedly shorter range than the Unni compound bows, but even their shields offered them only rudimentary protection.
However, the dense formation, in which they lined up, gave the barbarian infantry the necessary cohesion to deal with the Unnic attacks. The Frankish infantry were a special case. They were equipped with heavy javelins, the angons and a deadly accurate war blade, the frajiska, from which they got their name (Franks). Both of these weapons had a limited range.
However, they provided their owners with even a limited ability to respond to the Unnic "fires". If the Huns were more discouraged than they should have been and got close enough, the angons and frajisks would literally harvest them, as they were capable of crushing even a chain breastplate.