A Military Life of Constantine the Great

Ian Hughes

• Publisher: Pen & Sword Military
• Year: 2021
• ISBN:
  9781526724243
• Topic: History
• Subtopic: Military & Maritime History
• Index: History

A new analysis of the strengths, organization, weapons, and tactics of the Roman army Constantine inherited and his military reforms. Much of Constantine I's claim to lasting fame rests upon his sponsorship of Christianity, and many works have been published assessing whether his apparent conversion was a real religious experience or a cynical political maneuver. However, his path to sole rule of the Roman Empire depended more upon the ruthless application of military might than upon his espousal of Christianity. He fought numerous campaigns, many against Roman rivals for Imperial power, most famously defeating Maxentius at the Battle of the Milvian Bridge. In this new study, Ian Hughes assesses whether Constantine would have deserved the title "the Great" for his military achievements alone, or whether the epithet depends upon the gratitude of Christian historians. All of Constantine's campaigns are narrated and his strategic and tactical decisions analyzed. The organization, strengths, and weaknesses of the Roman army he inherited are described and the effect of both his and his predecessors' reforms discussed. The result is a fresh analysis of this pivotal figure in European history from a military perspective.

Chapter One

Background

It is hard to do justice to the complex history of the Roman Empire in the third century without the need for at least one major book. The sources for the period reflect the chaotic history of the century in that they are confusing and fragmentary. In addition, the much-maligned Scriptores Historiae Augustae (Authors on the History of the Emperors, sometimes known as the Augustan History, henceforward SHA) has a chapter entitled ‘Tyranni Triginta’ (‘Thirty Tyrants’) which purports to be a list of usurpers who rebelled against Gallienus (r. 253–260). Although many are either imaginary or placed during the wrong reign, there are still many that are accurately recorded, as evidenced largely from these men issuing coins that have since been found. The fact that so many usurpers are at least proposed is a clear indication of how confused the situation was between 235 and 284. To compress events into a single chapter and cover all of them in any depth is impossible. Yet despite the difficulties, to understand the reasoning behind the military and political changes that took place during the lifetime of Constantine it is necessary to appreciate why such change was deemed necessary and so a brief recounting of the major events is given here.

The Third-Century Crisis

The assassination by his own troops of the emperor Severus Alexander, the last of the Severan dynasty, in 235 marks the beginning of the troubles known by historians as the Third-Century Crisis. He was succeeded by Maximinus I ‘Thrax’ (the Thracian), a man who had risen through the ranks. Maximinus was acclaimed by his fellow soldiers rather than being a senator of senior rank chosen by the Senate. Despite victories over external enemies, including the Alamanni, the Dacians and the Sarmatians on the northern frontier, Maximinus’ reign was threatened by the revolt of Gordian I and his son Gordian II in Africa. The revolt was quickly defeated. However, the Senate in Rome had supported the Gordians so they appointed new joint emperors called Pupienus and Balbinus to continue the opposition to Maximinus. Marching to defeat the rebellion, in 238 Maximinus was assassinated by his troops during a siege of Aquileia. The cycle of revolt and assassination was to be more or less replicated for roughly the next fifty years.

Although nominally joint emperors for a short period in 238 and 239, Pupienus and Balbinus continuously argued and were not popular with the people. In order to gain popularity, they appointed the grandson of Gordian I, also called Gordian, as Caesar (junior ruler). Despite this attempt to gain popularity, their continuous bickering resulted in them both being assassinated by the Praetorian Guard.

Their Caesar, Gordian III, now assumed the purple and ruled between 238/9 and 244. Due to his youth – he was only 13 when he became emperor – he needed the support of the Senate and aristocracy of Rome, and especially the support of Timethiseus, his father-in-law and Praetorian Prefect. During his reign there was the revolt of Sabinianus in Africa in 240–1. Of more importance, the Sasanid Persians were defeated in 243 at the Battle of Resaena, but then Timethiseus died and was succeeded by Gaius Julius Priscus and Marcus Julius Philippus as Praetorian Prefects. In the following year Gordian in person suffered a defeat against Persia at the Battle of Misiche. Gordian’s fate is unclear: the mainly Persian sources record that he died in the battle, whereas the majority of the Roman sources claim that he was assassinated by his own troops following the defeat.

Whatever the case, he was succeeded by the Praetorian Prefect Marcus Julius Philippus, better known as Philip ‘Arabus’ (the Arab) who ruled from 244 to 249. Philip established a peace with Persia, but was then forced to face an invasion of the Balkans by the Carpi, before war once again broke out with Persia, both wars probably in 245. In 248 there was a rebellion in the Balkans under Pacatianus which in turn resulted in further barbarian attacks upon the Empire, as well as more rebellions. As events turned against him, Philip offered to resign but instead was supported by a man named Decius, who led the troops to defeat both Pacatianus and the invading barbarians. Unfortunately for Philip, the troops then demanded that Decius be made emperor. Decius marched on Italy and defeated Philip in battle. Philip was either killed in the battle or assassinated by his own troops.

Decius, who ruled between 249 and 251, appears in some respects to have been an able military commander and organizer who in better times may have been able to restore the fortunes of the Empire. Fate decided otherwise. It was during his reign that the Goths first appeared in strength and invaded the Empire. Although at first able to seize the initiative, Decius made the mistake of attacking the Goths on terrain more favourable to them and he was killed in the Battle of Abritus.

Although Decius’ son Hostilian declared himself emperor, the troops acclaimed Trebonianus Gallus, who ruled from 251 to 253. To avoid a civil war in the first year of his reign, Gallus accepted Hostilian as a co-ruler but Hostilian then died of the plague in the same year. Gallus’ reign was dominated by rebellions, losses against the Sasanid Persians and invasions of Asia Minor by northern tribes. The latter were defeated by a general named Aemilianus, whose troops followed the new-born tradition of acclaiming a successful general. Aemilianus then invaded the West, due to which Gallus was killed by his own troops. Aemilianus thus became emperor, but only reigned for a few months before being assassinated by his own men when the general Valerian, who had supported Gallus, was in turn proclaimed Emperor by his troops.

Valerian ruled from 253 to 260. Valerian quickly appointed his son Gallienus as Caesar with Gallienus taking control of the West while Valerian headed East to face the Sasanid Persians, who had again invaded during a time of crisis in Rome. In the West, Gallienus won many battles against barbarian invaders, but in 260 was faced with the revolt of Ingenuus. Although this was quickly defeated, it had its origins in events in the East. Valerian had restored order in the East over a number of years, but after his army had been devastated by an outbreak of plague he was defeated by the Persians at the Battle of Edessa in 260. Although a truce was agreed, the Persian ruler broke the terms and Valerian was taken prisoner by the Persians during the ensuing negotiations.

Gallienus then became sole Emperor, ruling in effect from 253 to 268. The revolt of Ingenuus was not the only one caused by Valerian’s defeat and capture. When in 260 an Alamannic invasion of Italy drew Gallienus to the region, a man named Regalianus also rebelled. Although he defeated a Sarmatian invasion, Regalianus was shortly after assassinated. However, these were not the most important rebellions that Gallienus had to face: these were the revolt of Macrianus in the East and Postumus in the West.

Macrianus was another who rebelled following the capture of Valerian, but he was defeated in 261. The importance of the rebellion lies in the fact that, needing to remain in the West, Gallienus now gave military command in the East to Odenathus, the ruler of the city-kingdom of Palmyra. Odenathus had defeated the Persian army in the campaign following Valerian’s defeat and it was he who defeated and killed the last supporters of Macrianus. Yet Gallienus’ decision to promote Odenathus was to have grave consequences both for Gallienus and his successors.

Gallienus had been unable to defeat Macrianus in person as he had to face the (almost) simultaneous revolt of Postumus in the West in 260. However, the campaign to remove Postumus was a failure and he would remain undefeated, becoming Emperor of a ‘realm’ known to later historians as the ‘Gallic Empire’ which would last until 274. This was in part due to the fact that Gallienus would be forced to spend much of his time dealing with further rebellions, as well as barbarian invasions, rather than focusing upon the rebellious ‘Empire’.

Gallienus managed to defeat these opponents – including a large Gothic invasion of the Balkans – but to further complicate his reign, Zenobia, ‘queen’ of Palmyra and wife of Odenathus (see above) had taken control of events after her husband’s death in 267 and proclaimed her son Vaballathus Emperor in the East. Gallienus now had two separate hostile ‘Roman Empires’ to deal with, but before this was possible the cavalry commander Aureolus rebelled in Italy. Gallienus defeated Aureolus in battle, but when he then laid siege to the pretender in Milan he would fall foul of yet another conspiracy, being killed by his own troops in 268.

His successor was Claudius II Gothicus (‘Victor over the Goths’) who ruled from 268 to 270. A man of ignoble birth and the first of the so-called ‘soldier-emperors’, he was another, like Decius, who may have been able to halt the Empire’s decline. Although Gallienus had defeated the Goths, they remained a danger. In 268/9 Claudius defeated the Goths at the Battle of Naissus, from which victory he took the epithet ‘Gothicus’. He then beat the Alamanni before turning his attention to the ‘Gallic Empire’. He reconquered Hispania and parts of southern Gaul, but before he could complete his military reconquest of the West, Claudius died of plague in 270.

Aurelian had been the general in command of at least part of the army during Claudius’ reign and it was he who now became Emperor, ruling from 270 to 275, but only after defeating Claudius’ brother Quintillus, who had also claimed the throne. Another military commander, he was forced to fight Vandals, Iuthungi and Sarmatians in Italy in 270, before facing an Alamannic invasion of Italy in 271. In addition, he then had to defeat the rebellions of Domitianus in Gaul in late 270-early 271, and a man named Septimius, and possibly another named Urbanus, in Dalmatia in 271/2.

After overcoming these obstacles, Aurelian began the reunification of the Empire. In 270 the Palmyrenes had begun to expand their control, conquering Egypt in 270 and Galatia in 271. Finally Aurelian had the time to face Zenobia. In 272 he led his army east and after a series of battles arrived at the city of Palmyra and so brought the Palmyrene Empire to an end. It is possible that on 27 February, in the same year as this important victory, the future Emperor Constantine was born in Naissus (Niš) in the province of Moesia.

With the East returned to Roman rule, in 274 Aurelian led his troops west. The ‘Gallic Empire’ was now in the hands of a man named Tetricus. However, Tetricus was not prepared to face Aurelian and his veteran armies and conceived a plan with Aurelian that when the armies came face to face, Tetricus would desert to Aurelian. This happened and, leaderless, the Gallic army was easily defeated. The ‘Gallic Empire’ was no more.

The Roman Empire was finally reunited. At this point Aurelian decided that the province of Dacia, on the further banks of the Danube, was now unsustainable and in 275 it was abandoned. Despite his considerable military victories, Aurelian did not have long to savour his successes: also in 275, while preparing to campaign against the Sasanid Persians, he was murdered by members of the Praetorian Guard.

Aurelian was succeeded by Tacitus, who ruled briefly from 275 to 276. In his short reign he won victories over invading Goths and the Heruls, before being forced to turn west by an invasion of Franks and Alamanni into Gaul. He was not to conduct the campaign, as he contracted a fever and died en route.

Tacitus was followed by his (possible) half-brother Florianus. However, the latter’s rule was extremely short – only a few months – although in that time he was forced to fight against the Heruls. It was brought to an end when the Eastern army declared their support for Probus, a governor in the East. Although the West supported Florianus, he was quickly defeated in battle by Probus, after which he was assassinated by his own troops.

Probus, who ruled from 276 to 282, led the armies which defeated the Goths in 277, the Alamanni in 278 and the Vandals in 279–80 and under his direction in 278 Gaul was cleared of invading Franks and in 279/280 the Blemmye were defeated in Egypt. Despite these victories, Probus had to face the rebellions of Julius Saturninus and Bonosus in 280 and of Proculus in 281. Once these had been dealt with, he began preparing for a campaign in the East when news arrived that a general named Carus had been proclaimed by his army. Unsurprisingly, following precedent Probus was quickly assassinated by his own troops.

Carus, who ruled from 282 to 283, raised his sons Carinus and Numerian to the post of joint Caesars before assuming Probus’ campaign against Persia. Carus took Numerian on the campaign, which was a great success: the Roman army campaigned deep into Persian territory and even crossed the River Tigris. However, in the middle of the campaign Carus was found dead in mysterious circumstances. He was succeeded by his sons Numerian and Carinus.

Numerian, who ruled for only a very short period from 283 to 284, was found dead in his litter on the return journey from the victory over the Persians: no explanation was offered for his death. During this period his brother and co-emperor Carinus, who ruled from 283 to 285, had won victories against Germanic tribes in the West.

However, one of Numerian’s military commanders, a man named Diocletian, declared that Numerian had been assassinated and was declared Augustus by the Eastern army. Carinus responded to the usurpation by gathering his troops and marching against Diocletian. The two armies met at the Battle of Margus, where Diocletian was victorious and Carinus was killed.

Diocletian was now the sole Roman Emperor. Under his rule the cycle of usurpation and barbarian invasion would gradually halt, giving Diocletian the time to pass legislation and put in place reforms aimed at restoring the Empire to a position of strength. Politically this was to be an attempt to reduce the number of usurpers emerging across the Empire, financially to increase the number of provinces to make the collection of taxes more efficient, as well as reduce the burden on provincial governors, while with regards to the military, the reform was aimed at improving the fighting and policing efficiency of the army. While the political and financial situation had deteriorated during the third century and Diocletian was to make drastic changes, few major changes had been made during the tumultuous years prior to Diocletian’s reign. On the other hand, with regard to the army, many of the reforms made by Diocletian had their genesis in incremental changes that occurred during the reigns of his many predecessors and so these need t...

Table of contents

• Cover
• Title
• Copyright
• Contents
• Introduction
• Abbreviations
• Chapter 1 Background
• Chapter 2 Diocletian and His Reforms
• Chapter 3 Constantius and Son
• Chapter 4 The Rise of Constantine
• Chapter 5 The Conquest of Northern Italy
• Chapter 6 The Battle of the Milvian Bridge
• Chapter 7 Constantine: Western Emperor
• Chapter 8 The Bellum Cibalense
• Chapter 9 Descent to War
• Chapter 10 The Final Conflict
• Chapter 11 The Reforms
• Chapter 12 Crispus and Fausta
• Chapter 13 Sole Emperor
• Chapter 14 Constantine’s Later Campaigns1
• Chapter 15 Aftermath and Conclusion
• Constantine’s Campaigns (Born c.272)
• Notes
• Select Bibliography
• Plate section