Roman Army: Late Principate

In this blog, we delve into the Roman army in the 3rd century AD. This period is characterized by the great crisis also known for its military anarchy. 

The Roman Empire was under Hadrian (117-138) at its greatest. From the 3rd century, Rome, instead of waging war and conquering new territories, was increasingly forced into a defensive position by marauding enemies and civil wars. As a result, the essential source of income obtained by plundering enemy lands dried up.

Instead, the countryside was opened up to economic devastation by marauders. Regular civil wars contributed to the depletion of the army's manpower, and recruiting replacement soldiers further strained the workforce. 

The Roman aristocracy developed a kleptocracy where power and self-interest were paramount. The legions also participated in this. In addition to their pay, soldiers received bonuses, for example, when appointing new emperors or the Tribuni or Consul who wanted to secure his power. This bonus culture led to the legionary's loyalty lying with whoever gave the best bonus. War meant bonuses, and thus the armies created their own work. In times without external war, they were not averse to proclaiming their own general as emperor and starting a civil war. The army needed increasingly larger bribes to remain loyal. Septimius Severus therefore increased the legionaries' pay and gave considerable donativum to the troops. But the large and continuous increase of these expenses caused problems for all his successors. His son Caracalla increased the annual pay again and gave the army many benefits in accordance with his father's advice to maintain their loyalty. 

A similar form of bribery can be seen in the populist bread and circuses and other political campaigns. This only led to even more corruption and inflation.

As a result, the 3rd century AD was a period in which the Roman Empire nearly collapsed under the combined pressure of repeated foreign invasions, civil wars, and economic inflation. 

During the crisis, there were at least 26 individuals who claimed the title of emperor, mostly prominent Roman generals who asserted imperial power over the entire or parts of the empire. An equal number of men were recognized by the Roman Senate as legitimate emperor during this period. 

At the height of the crisis in 268, the empire had fragmented into three competing states: the Gallic Empire (with the Roman provinces of Gaul, Britannia, and temporarily Hispania), the Palmyrene Empire (with the eastern provinces of Syria, Palaestina, and Aegyptus), and in between them the Roman Empire, with Italy as its power center.

In 212 AD, Emperor Caracalla granted citizenship to all free inhabitants of the Roman Empire through his Constitutio Antoniniana. This meant that no distinction was made between citizens, who were mainly ethnic Italians, and non-citizens (peregrini). As a result, all free citizens could participate as legionaries in the army. From that moment, the distinction between legionaries and auxiliary troops was removed, causing both to increasingly resemble each other. This also meant that superiority and the associated performance culture became more centered around the individual rather than ethnicity. Therefore, it became important to recruit more specialized troops from the foederati, allies of the Roman Empire from non-Roman areas. Foederati were not always reliable, and between the 3rd and 5th centuries, relations with these peoples regularly shifted between alliance and war. 

Both the disappearance of the auxilia and the influx of foederati had an increasingly significant impact after the 2nd half of the 3rd century AD. Legionaries from the first half of the 3rd century were still recognizable as the stereotypical 'legionary', this changed in the 2nd half of the 3rd century AD when a cultural mix between Roman and predominantly Germanic emerged. This change could be seen in everything such as clothing, art, and armor. 

Due to the many internal conflicts, the Roman armies were no longer able to defend the Empire's borders as they had previously done. This led to multiple invasions by 'barbarian peoples'. There were frequent invasions on the Rhine and Danube borders by tribes, including the Goths, Vandals, and Alemanni, as well as attacks by the Sassanids in the east. 

In the 1st half of the 3rd century AD, the equipment of the legionary changed. This was possibly partly a consequence of the Germanic influences in the army. Legionnaires from this time were still recognizable as the 'stereotypical' legionnaire, although this would change in the second half of the 3rd century.

Around this time, the galea type helmet was increasingly replaced by the type Niederbieber helmets. These helmets were more enclosed, with the cheek plates protecting a larger part of the side of the face. The eyebrow protector also became wider, offering more protection against downward strikes and falling projectiles, similar to the later medieval kettle hat. Although it was originally stated that this type of helmet was exclusively used by cavalrymen, this is incorrect. Infantrymen also used these helmets, only the helmets with mask visors were probably used solely for cavalry purposes.

The lorica segmentata remained in use but gradually fell out of favor. The lorica squamata and the lorica hamata or chainmail shirt were popular among both infantrymen and cavalrymen. 

The scutum was still in use until the second half of the 3rd century, but was then phased out for an oval type shield.

Around this time, the the pilum was equipped with an extra wide bullet, possibly to keep it javelin straight in the air or to give it more impact.

This was the last period in which certain models of the gladius were used, after which it was completely replaced by the longer spatha. The clothing of 'legionaries' from this time was strongly influenced by Germanic styles, the trousers became acceptable, and shorter tunics and Germanic types of cloaks were also worn.

The provision of more protective and expensive armor to legionaries was likely due to non-military reasons: the army emphasized their social superiority, just as it did with higher wages. During the 3rd century, when all peregrini received citizenship and legionaries thereby lost their social superiority, the lorica segmentata and the scutum disappeared.

In the 3rd century, the segmentata seem to have been phased out and troops are depicted with mail shirts (primarily) or scale armour, the standard armor of the auxilia from the 2nd century. 

The reign of Aurelian (270–275) marked a turning point in this crisis period. Aurelian managed to reunite the empire by defeating the two seceded states and implemented a series of reforms that helped to restore some stability to the Roman economy. The end of the crisis is considered to be the moment when Diocletian took power in 284 and thoroughly reformed the Roman imperial government, economy, and military. In particular, the military reforms are seen as a crucial turning point in Roman history, marking the beginning of the Dominate period.

Rome lost its role as the political center of the empire during the third century, although it remained ideologically important. To legitimize and secure their rule, the emperors of the third century especially needed military successes. The decision-making center shifted away from Rome to the places where the emperor was with his armies, usually in the east. This led to the relocation of the capital to four cities: Milan, Trier, Nicomedia, and Sirmium, and later to Constantinople. The Senate ceased to be the main governing body, and instead, members of the equestrian order, who formed the officer corps of the army, gained increasing influence.

The Dominate is a period in the history of the Roman Empire during late antiquity. It followed the phase known as the Principate. The beginning of the Dominate is usually placed at the accession of Emperor Diocletian in 284, after the crisis of the third century (235–284).

The Dominate is often seen as a more authoritarian, less collegial, and bureaucratic system of governance than the Principate, from which it emerged. This form of government arose in response to the fifty years of chaos during the crisis of the third century. The continuous claimants to the throne, military uprisings, and border conflicts exposed the weaknesses of Roman governance. This led to a gradual shift from a collegial emperorship to a more autocratic rule from 285 onwards.

Important features of the Dominate included the exclusion of the senatorial elite from high military positions and the rise of the equites (the equestrian order), the reform of the army with the establishment of mobile field armies, changes in imperial clothing and ceremonial practices, a religious policy aimed at unity, large-scale monetary reforms, and the formation of an overarching imperial bureaucracy.

Although Diocletian is often seen as the founder of the Dominate, many innovations originated with earlier emperors, especially Aurelian (270–275). Some reforms even date back to the reigns of Gallienus (253–268) and Trajan (98–117), under whom the equestrians played an increasingly important role in the governance of Rome and the empire. The transition to the Dominate was therefore not a sudden change; only under Constantine the Great, around 337, were the reforms largely completed.

The traditionally well-known large legions were drastically changed. Instead of a static network, the army was now kept at tactical locations behind the Roman frontier. Mobility became more important and cavalry began to play an increasingly significant role. During the reign of Diocletian (284–305) and his successor Constantine the Great, the traditional 5,000-man strong legions were completely split into cohorts of 1,000 to 2,000 troops. The army was divided into two main categories:

• Comitatenses: the mobile field armies, strategically deployed in conflicts.
• Limitanei: border guards permanently stationed along the limes (border defenses).

This allowed cities and provinces to receive reinforcements more quickly, while the border defense held against sudden incursions.

In the 3rd century, the appearance of the Roman legionary changed significantly. However, there were still many similarities in their armor that can be compared to those of earlier periods in the Principate. After the crisis of the 3rd century, both military equipment and the administrative infrastructure of the Roman Empire changed significantly. If a few very capable emperors had not seized power at the end of the 3rd century, the Roman Empire would have ceased to exist during this crisis.