Roman Civil Wars of 235-394

At issue: Control of the Roman Empire

Date: March, 235-September 9, 394

Location: Pannonia, North Africa, Italy, Verona, Palmyra, Rome, Emesa, Châlons, Gaul, Britain, Asia Minor, Siscia, Poetovio

Combatants: Various Roman emperors vs. usurpers

Principal commanders:Roman emperors, Maximinus (d. 238), Gallienus (d. 268), Aurelian (c. 215-275), Diocletian (d. 316), Constantine (285-337), Theodosius I (d. 395)

Principal battles: Verona, Caelian Mount, Emesa, Châlons, Margus River, Milvian Bridge, Adrianople, Chrysopolis, Mursa, Mons Seleucus, Frigidus

Result: An empire weakened against barbarian attacks and soon to split permanently into eastern and western divisions

Background

By the first century before the common era, Rome ruled most of the lands around the Mediterranean Sea, but the empire suffered from internal political weakness. Military units were often more loyal to their commanders than to the state, resulting in civil wars. In 27 b.c.e., Octavian (later known as Augustus), defeated his opponents and became the first emperor, giving himself the title of imperator, literally “commander.” A series of strong successors and prudent administration created an internal peace (Pax Romana) that would last until 180 c.e. During the next forty-five years, under Emperor Severus Alexander, Rome achieved intermittent peace, but the emperor’s murder in 235 led to about fifty years of almost constant civil war. In this anarchistic period, almost all of the approximately thirty emperors, some reigning simultaneously in different provinces, were murdered. The civil wars continued until 394 and took place simultaneously with wars against barbarians, primarily Germanic and Persian peoples, some of whom took sides in the civil strife.

Action

In March, 235, troops from Pannonia (modern-day Hungary) successfully revolted against Severus Alexander, proclaiming their commander, Maximinus Thrax, as the new emperor. On March 19, 238, North African troops under Gordian I revolted, proclaiming him emperor. Gordian I died after his son, Gordian II, was killed in battle against Maximinus’s troops. Maximinus invaded Italy but was murdered by his troops after failing to take Aquileia. Emperor Gordian III put down military revolts in Africa, but was murdered by one of his soldiers in February, 244. His successor, Philip the Arab (M. Julius Philippus Arabus), defeated military revolts in both the eastern and western dominions and became coemperor with Decius, but the two quarreled. Decius’s troops were victorious near Verona (September, 249). After defeating provincial revolts, Decius was killed by the Goths. From 251 to 253, Trebonianus Gallus was emperor, and Aemilian usurped the throne in 253. A few months later, Aemilian was killed by his own troops, and Valerian seized the throne. After the Persians captured Valerian in 260, his son, Gallienus, became emperor. The new emperor suppressed military revolts in the Eastern Empire.

Odaenathus, ruler of Palmyra (modern-day Syria), allied himself with Rome, defeated Persia, and was proclaimed coemperor with Gallienus but was assassinated in 267. Palmyra, led by Zenobia, Odaenathus’s widow, revolted. In the western dominions, Postumus also revolted. Gallienus defeated supporters of Postumus but was assassinated in August, 268, by a conspiracy that included Claudius II Gothicus, who became emperor. Postumus’s rebellion was suppressed in 269. Claudius died in 270, and Quintilius became emperor. In April, 270, Aurelian rose against Quintilius, whose armies abandoned him. Later that year, Aurelian defeated a revolt in Rome; thousands of rebels died on the Caelian Mount (270) outside the city. Aurelian defeated rebellions in many parts of the empire, notably that of the Palmyrenes under Zenobia and Vaballathus, who had conquered much of Rome’s eastern dominions. After a victory at Emesa (271), Aurelian’s army induced Palmyra to surrender. Aurelian defeated Tetricus near Châlons (274), restoring Gaul to the empire. In 275, Aurelian was assassinated and succeeded by Tacitus, who suppressed military revolts in the eastern dominions before dying in 276. In the ensuing civil war, Probus became emperor. After Probus was killed by his troops in 282, Carus became emperor. After Carus died in 283, his son Carinus, who ruled with Numerian, was defeated in the valley of the Margus River (285) in Pannonia, by Diocletian, who became emperor, ending fifty years of military anarchy.

In 286, Diocletian and Carausius defeated the peasant revolt of the Bagaudae in Gaul. On April 1, 286, Diocletian named Maximian coemperor. In 287-288, Carausius rebelled in Britain, but his attempts to expand into southern Gaul were prevented by Maximian’s naval attack in 289. Diocletian defeated the forces of Carausius’s successor, Allectus in 294. That same year, Achilleus declared himself emperor in northern Egypt but was executed by Diocletian in 296. After Diocletian’s abdication in 305, Marcus Aurelius Valerius Maxentius and Domitius Alexander rebelled against the coemperors Galerius and Licinius. After Galerius died in 311, war broke out between Licinius and the former coemperor Maximian. Constantine, an imperial family member, supported Licinius, defeating Maxentius, who had 100,000 men to Constantine’s 40,000, at the Milvian Bridge outside Rome (October 28, 312). Maxentius drowned as his troops retreated. In 314, a brief, indecisive war ensued between Constantine and Licinius, ending in compromise. In 324, war began anew. At Adrianople (324), Constantine, after a preliminary attack by 5,000 of his archers, defeated Licinius, with 34,000 casualties. Constantine’s navy besieged Byzantium (later Constantinople); 130 of Licinius’s galleys were destroyed. Licinius was decisively defeated at Chrysopolis (September 18, 324). Constantine was now sole ruler of the Roman Empire.

After Constantine’s death in 337, an uneasy peace prevailed until Magnentius warred with the Emperor Constantius II, who won at Mursa (September 28, 351). Constantius’s new tactic used flanking action, with mounted archers and mailed cavalry. Constantius lost about 30,000 men and Magnentius 24,000. Magnentius retreated into Gaul and was defeated at Mons Seleucus (summer, 353). When the troops in Britain proclaimed Magnus Maximus emperor, Gaul was invaded, and the Western emperor, Gratian, deserted by his troops, was killed (August 25, 383). Maximus invaded Italy. The Emperor Theodosius I was victorious at Siscia and Poetovio, driving Maximus back to Italy, where he surrendered. In 392, Eugenius revolted but was defeated at Frigidus (September 6, 394) by Theodosius.

Aftermath

Theodosius, the last emperor of both the eastern and western dominions, died in 395. The empire was divided between his two sons and was never again united.

Fifty Years of Anarchy: Roman Emperors from 235 through 284

Bibliography

Dixon, K. R., and P. Southern. The Late Roman Army. London: B. T. Batsford, 1996.

Elton, H. Warfare in Roman Europe, a.d. 350-425. Oxford, England: Clarendon Press, 1996.

Isaac, B. The Limits of Empire: The Roman Army in the East. Rev. ed. Oxford, England: Clarendon Press, 1993.