The World of the Ancient Romans - Warfare
Principate (27 BC–AD 235)
Between the reigns of the emperors Augustus and Trajan, the Roman Empire achieved great territorial gains in both the East and the West. In the West, following several defeats in 16 BC, Roman armies pushed north and east out of Gaul to subdue much of Germania. Despite the loss of a large army almost to the man in Varus' famous defeat in the Battle of the Teutoburg Forest in AD 9.
Rome recovered and continued its expansion up to and beyond the borders of the known world. The Romans invaded Britain in AD 43, forcing their way inland, and building two military bases to protect against rebellion and incursions from the north, from which Roman troops built and manned Hadrian's Wall.
Emperor Claudius ordered the suspension of further attacks across the Rhine, setting what was to become the permanent limit of the Empire's expansion in this direction. Further east, Trajan turned his attention to Dacia. Following an uncertain number of battles, Trajan marched into Dacia, besieged the Dacian capital and razed it to the ground. With Dacia quelled, Trajan subsequently invaded the Parthian empire to the east, his conquests taking the Roman Empire to its greatest extent.
In AD 69, Marcus Salvius Otho had the Emperor Galba murdered and claimed the throne for himself, but Vitellius had also claimed the throne. Otho left Rome, and met Vitellius at the First Battle of Bedriacum, after which the Othonian troops fled back to their camp, and the next day surrendered to the Vitellian forces. Meanwhile, the forces stationed in the Middle East provinces of Judaea and Syria had acclaimed Vespasian as emperor. Vespasians' and Vitellius' armies met in the Second Battle of Bedriacum, after which the Vitellian troops were driven back into their camp. Vespasian, having successfully ended the civil war, was declared emperor.
The First Jewish-Roman War, sometimes called The Great Revolt, was the first of three major rebellions by the Jews of Judaea Province against the Roman Empire. Earlier Jewish successes against Rome only attracted greater attention from Emperor Nero, who appointed general Vespasian to crush the rebellion. By the year 68, Jewish resistance in the North had been crushed. In 115, revolt broke out again in the province, leading to the second Jewish-Roman war known as the Kitos War, and again in 132 in what is known as Bar Kokhba's revolt. Both were brutally crushed.
Due in large part to their employment of powerful heavy cavalry and mobile horse-archers, the Parthian Empire was the most formidable enemy of the Roman Empire in the east. Trajan had campaigned against the Parthians and briefly captured their capital, putting a puppet ruler on the throne, but the territories were abandoned. A revitalised Parthian Empire renewed its assault in 161, and defeated two Roman armies. General Gaius Avidius Cassius was sent in 162 to counter the resurgent Parthia. The Parthian city of Seleucia on the Tigris was destroyed, and the Parthians made peace but were forced to cede western Mesopotamia to the Romans.
In 197, Emperor Septimius Severus waged a brief and successful war against the Parthian Empire, during which time the Parthian capital was sacked, and the northern half of Mesopotamia was restored to Rome. Emperor Caracalla marched on Parthia in 217 from Edessa to begin a war against them, but he was assassinated while on the march. In 224, the Parthian Empire was crushed not by the Romans but by the rebellious Persian vassal king Ardashir, who revolted, leading to the establishment of Sassanid Empire of Persia, which replaced Parthia as Rome's major rival in the East.
Barracks and Illyrian emperors (235-284) and Dominate (284–395)
Although the exact historicity is unclear, some mix of Germanic peoples, Celts, and tribes of mixed Celto-Germanic ethnicity were settled in the lands of Germania from the first century onwards. The essential problem of large tribal groups on the frontier remained much the same as the situation Rome faced in earlier centuries, the third century saw a marked increase in the overall threat.
The assembled warbands of the Alamanni frequently crossed the border, attacking Germania Superior such that they were almost continually engaged in conflicts with the Roman Empire. However, their first major assault deep into Roman territory did not come until 268. In that year the Romans were forced to denude much of their German frontier of troops in response to a massive invasion by another new Germanic tribal confederacy, the Goths, from the east. The pressure of tribal groups pushing into the Empire was the end result of a chain of migrations with its roots far to the east.
The Alamanni seized the opportunity to launch a major invasion of Gaul and northern Italy. However, the Visigoths were defeated in battle that summer and then routed in the Battle of Naissus. The Goths remained a major threat to the Empire but directed their attacks away from Italy itself for several years after their defeat.
The Alamanni on the other hand resumed their drive towards Italy almost immediately. They defeated Aurelian at the Battle of Placentia in 271 but were beaten back for a short time, only to reemerge fifty years later. In 378 the Goths inflicted a crushing defeat on the Eastern Empire at the Battle of Adrianople.
At the same time, Franks raided through the North Sea and the English Channel, Vandals pressed across the Rhine, Iuthungi against the Danube, Iazyges, Carpi and Taifali harassed Dacia, and Gepids joined the Goths and Heruli in attacks round the Black Sea. At the start of the fifth century AD, the pressure on Rome's western borders was growing intense.
A military that was often willing to support its commander over its emperor meant that commanders could establish sole control of the army they were responsible for and usurp the imperial throne. The so-called Crisis of the Third Century describes the turmoil of murder, usurpation and in-fighting that is traditionally seen as developing with the murder of the Emperor Alexander Severus in 235.
Emperor Septimius Severus was forced to deal with two rivals for the throne: Pescennius Niger and then Clodius Albinus. Severus' successor Caracalla passed uninterrupted for a while until he was murdered by Macrinus, who proclaimed himsef emperor in his place. The troops of Elagabalus declared him to be emperor instead, and the two met in battle at the Battle of Antioch in AD 218, in which Macrinus was defeated.
However, Elagabalus was murdered shortly afterwards and Alexander Severus was proclaimed emperor, who at the end of his reign was murdered in turn. His murderers raised in his place Maximinus Thrax. However, just as he had been raised by the army, Maximinus was also brought down by them and was murdered when it appeared to his forces as though he would not be able to best the senatorial candidate for the throne, Gordian III.
Gordian III's fate is not certain, although he may have been murdered by his own successor, Philip the Arab, who ruled for only a few years before the army again raised a general to proclaimed emperor, this time Decius, who defeated Philip in the Battle of Verona to seize the throne. Gallienus, emperor from AD 260 to 268, saw a remarkable array of usurpers. Diocletian, a usurper himself, defeated Carinus to become emperor. Some small measure of stability again returned at this point, with the empire split into a Tetrarchy of two greater and two lesser emperors, a system that staved off civil wars for a short time until AD 312. In that year, relations between the tetrarchy collapsed for good. From AD 314 onwards, Constantine the Great defeated Licinius in a series of battles. Constantine then turned to Maxentius, beating him in the Battle of Verona and the Battle of Milvian Bridge.
After overthrowing the Parthian confederacy, the Sassanid Empire that arose from its remains pursued a more aggressive expansionist policy than their predecessors and continued to make war against Rome. In 230, the first Sassanid emperor attacked Roman territory, and in 243, Emperor Gordian III's army defeated the Sassanids at the Battle of Resaena.
In 253 the Sassanids under Shapur I penetrated deeply into Roman territory, defeating a Roman force at the Battle of Barbalissos and conquering and plundering Antiochia. In 260 at the Battle of Edessa the Sassanids defeated the Roman army and captured the Roman Emperor Valerian.
There was a lasting peace between Rome and the Sassanid Empire between 297 and 337 following a treaty between Narseh and Emperor Diocletian. However, just before the death of Constantine I in 337, Shapur II broke the peace and began a twenty-six year conflict, attempting with little success to conquer Roman fortresses in the region. Emperor Julian met Shapur in 363 in the Battle of Ctesiphon outside the walls of the Persian capital. The Romans were victorious but were unable to take the city and were forced to retreat. There were several later wars.
Collapse of the Western Empire (395–476)
After the death of Theodosius I in 395, the Visigoths renounced their treaty with the Empire and invaded northern Italy under their new king Alaric, but were repeatedly repulsed by the Western commander-in-chief Stilicho. However, the limes on the Rhine had been depleted of Roman troops, and in early 407 Vandals, Alans, and Suevi invaded Gaul en masse and, meeting little resistance, proceeded to cross the Pyrenees, entering Spain in 409.
Stilicho became a victim of court intrigues in Ravenna (where the imperial court resided since 402) and was executed for high treason in 408. After his death, the government became increasingly ineffective in dealing with the barbarians, and in 410 Rome was sacked by the Visigoths.
Under Alaric's successors, the Goths then settled in Gaul (412-418) as foederati and for a while were successfully employed against the Vandals, Alans, and Suevi in Spain. Meanwhile, in the turmoil of the preceding years, Roman Britain had been abandoned.
After Honorius' death in 423, the Eastern empire installed the weak Valentinian III as Western Emperor in Ravenna. After a violent struggle with several rivals, Aetius rose to the rank of magister militum. Aetius was able to stabilize the empire's military situation somewhat, relying heavily on his Hunnic allies. With their help he defeated the Burgundians, who had occupied part of southern Gaul after 407, and settled them as Roman allies in the Savoy (433). Later that century, as Roman power faded away, the Burgundians extended their rule to the Rhone valley.
Meanwhile, pressure from the Visigoths and a rebellion by the governor of Africa, Bonifacius, had induced the Vandals under their king Gaiseric to cross over from Spain in 429. After capturing Carthage, they established an independent state with a powerful navy (439), which was officially recognised by the Empire in 442. The Vandal fleet from then on formed a constant danger to Roman seafare and the coasts and islands of the Western and Central Mediterranean.
In 444, the Huns, who had been employed as Roman allies by Aetius, were united under their king Attila, who invaded Gaul and was only stopped with great effort by a combined Roman-Germanic force led by Aetius in the Battle of Chalons (451). The next year, Attila invaded Italy and proceeded to march upon Rome, but he halted his campaign and died a year later in 453.
Aetius was murdered by Valentinian in 454, who was then himself murdered by the dead general's supporters a year later. With the end of the Theodosian dynasty, a new period of dynastic struggle ensued. The Vandals took advantage of the unrest, sailed up to Rome, and plundered the city in 455. As the barbarians settled in the former provinces, nominally as allies but de facto operating as independent polities, the territory of the Western Empire was effectively reduced to Italy and parts of Gaul.
From 455 onward, several emperors were installed in the West by the government of Constantinople, but their authority only reached as far as the barbarian commanders of the army and their troops (Ricimer (456-472), Gundobad (473-475)) allowed it to. In 475, Orestes, a former secretary of Attila, drove Emperor Julius Nepos out of Ravenna and proclaimed his own son Romulus Augustus as emperor.
In 476, Orestes refused to grant Odoacer and the Heruli federated status, prompting the latter to kill him, depose his son and send the imperial insignia to Constantinople, installing himself as king over Italy. Although isolated pockets of Roman rule continued even after 476, the city of Rome itself was under the rule of the barbarians, and the control of Rome over the West had effectively ended. The Eastern Roman or Byzantine Empire endured until 1453 with the capture of Constantinople by the Ottoman Turks led by Mehmed II.