Tetrarchy
Encyclopedia
The term Tetrarchy describes any system of government where power is divided among four individuals, but usually refers to the tetrarchy instituted by Roman Emperor
Diocletian
in 293, marking the end of the Crisis of the Third Century
and the recovery of the Roman Empire
. This Tetrarchy lasted until c.313, when internecine conflict eliminated most of the claimants to power, leaving Constantine
in the West and Licinius
in the East.
, established after the death of Herod the Great
, is the most famous example of the antique tetrarchy. The term was understood in the Latin world as well, where Pliny the Elder
glossed it as follows: "each is the equivalent of a kingdom, and also part of one" (regnorum instar singulae et in regna contribuuntur).
The sense in which the term was used by the ancients is distinct from the sense it carries in modern literature on Diocletianic government: whereas the Judaean tetrarchy was a set of four independent and distinct states, where each tetrarch ruled a quarter of a kingdom, the Diocletianic tetrarchy was a college, led by a single supreme leader. When later authors described the period, this is what they emphasized: Ammianus
has Constantius II admonish Julian for disobedience by appealing to the example in submission set by Diocletian's lesser colleagues; Julian himself would compare the Diocletianic tetrarchs to a chorus surrounding a leader, speaking in unison under his command. Only Lactantius
, a contemporary of Diocletian and a deep ideological opponent of the Diocletianic state, referred to the tetrarchs as a simple multiplicity of rulers.
Much modern scholarship was written without the term. Although Edward Gibbon
pioneered the description of the Diocletianic government as a "new empire", he never used the term. Neither did Theodor Mommsen
. It did not appear in the literature until 1887, when it was used by the schoolmaster Hermann Schiller in a two-volume handbook on the Roman Empire, Geschichte der Römischen Kaiserzeit. Schiller called it "die diokletianische Tetrarchie". The term did not catch on in the literature, however, until Otto Seeck
used it in 1897.
("rule of two"), involved the designation of the general Maximian
as co-emperor — firstly as Caesar
(junior emperor) in 285, followed by his promotion to Augustus
in 286. Diocletian
took care of matters in the Eastern regions of the Empire while Maximian similarly took charge of the Western regions. In 293, feeling more focus was needed on both civic and military problems, Diocletian, with Maximian's consent, expanded the imperial college by appointing two Caesars (one responsible to each Augustus) — Galerius
and Constantius Chlorus
.
In 305, the senior emperors jointly abdicated and retired, allowing Constantius and Galerius to be elevated in rank to Augusti. They in turn appointed two new Caesars — Severus II
in the east under Constantius, and Maximinus
in the west under Galerius — thereby creating the second Tetrarchy.
The four Tetrarchs based themselves not at Rome but in other cities closer to the frontiers, mainly intended as headquarters for the defence of the Empire against bordering rivals (notably Sassanian Persia) and barbarian
s (mainly Germanic, and an endless procession from the eastern steppe; many nomadic or elsewhere chased tribes) at the Rhine and Danube. These centres are known as the "Tetrarchic capitals". Although Rome ceased to be an operational capital, the "Eternal City" continued to be nominal capital of the entire Roman Empire, not reduced to the status of a province but under its own, unique Prefect of the City (praefectus urbis, later copied in Constantinople).
The four Tetrarchic capitals were:
Aquileia
, a port on the Adriatic coast, and Eboracum
(modern York
, in northern England near the Celtic tribes of modern Scotland and Ireland), were also significant centres for Maximian and Constantius respectively.
In terms of regional jurisdiction there was no precise division between the four Tetrarchs, and this period did not see the Roman state actually split up into four distinct sub-empires. Each emperor had his zone of influence within the Roman Empire, but little more, mainly high command in a 'war theatre'. Each Tetrarch was himself often in the field, while delegating most of the administration to the hierarchic bureaucracy headed by his respective Pretorian Prefect, each supervising several Vicarii, the governors-general in charge of another, lasting new administrative level, the civil diocese
. For a listing of the provinces, now known as eparchy
, within each quarter (known as a praetorian prefecture), see Roman province
.
In the West, the Augustus Maximian controlled the provinces west of the Adriatic Sea and the Syrtis, and within that region his Caesar, Constantius, controlled Gaul and Britain. In the East, the arrangements between the Augustus Diocletian and his Caesar, Galerius, were much more flexible.
However, it appears that some contemporary and later writers, such as the Christian author Lactantius
, and Sextus Aurelius Victor (who wrote about fifty years later and from uncertain sources), misunderstood the Tetrarchic system in this respect, believing it to have involved a stricter division of territories between the four emperors.
The Tetrarchs appeared identical in all official portraits. Coinage dating from the Tetrarchic period depicts every emperor with identical features — only the inscriptions on the coins indicate which one of the four emperors is being shown. The Byzantine sculpture Portrait of the Four Tetrarchs (pictured at right) shows the Tetrarchs again with identical features and wearing the same military costume.
and Probus were prepared to accompany their armies thousands of miles between war regions, this was not an ideal solution. Furthermore, it was risky for an emperor to delegate power in his absence to a subordinate general, who might win a victory and then be proclaimed as a rival emperor himself by his troops (which often happened). All members of the imperial college, on the other hand, were of essentially equal rank, despite two being senior emperors and two being junior; their functions and authorities were also equal.
Under the Tetrarchy a number of important military victories were secured. Both the Dyarchic and the Tetrarchic system ensured that an emperor was nearby to every crisis area to personally direct and remain in control of campaigns simultaneously on more than just one front. After suffering a defeat by the Persians in 296, Galerius crushed Narseh
in 298 — reversing a series of Roman defeats throughout the century — capturing members of the imperial household and a substantial amount of booty and gaining a highly favourable peace treaty, which secured peace between the two powers for a generation. Similarly, Constantius defeated the British usurper Allectus
, Maximian pacified the Gauls, and Diocletian crushed the revolt of Domitianus
in Egypt
.
When in 305 the 20-year term of Diocletian and Maximian ended, both abdicated. Their Caesares, Galerius and Constantius Chlorus, were both raised to the rank of Augustus, and two new Caesares were appointed: Maximinus
(Caesar to Galerius) and Flavius Valerius Severus
(Caesar to Constantius). These four formed the second Tetrarchy.
However, the system broke down very quickly thereafter. When Constantius died in 306, Galerius promoted Severus to Augustus while Constantine the Great was proclaimed Augustus to succeed his father Constantius, by his father's troops. At the same time, Maxentius
, the son of Maximian, resenting having been left out of the new arrangements, defeated Severus before forcing him to abdicate and then arranging his murder in 307. Maxentius and Maximian both then declared themselves Augusti. By 308 there were therefore no fewer than four claimants to the rank of Augustus (Galerius, Constantine, Maximian and Maxentius), and only one to that of Caesar (Maximinus).
In 308 Galerius, together with the retired emperor Diocletian and the supposedly retired Maximian, called an imperial "conference" at Carnuntum
on the River Danube. The council agreed that Licinius
would become Augustus in the West, with Constantine as his Caesar. In the East, Galerius remained Augustus and Maximinus remained his Caesar. Maximian was to retire, and Maxentius was declared an usurper. This agreement proved disastrous: by 308 Maxentius had become de facto ruler of Italy and Africa even without any imperial rank, and neither Constantine nor Maximinus — who had both been Caesares since 306 and 305 respectively — were prepared to tolerate the promotion of the Augustus Licinius as their superior.
After an abortive attempt to placate both Constantine and Maximinus with the meaningless title filius Augusti ("son of the Augustus", essentially an alternative title for Caesar), they both had to be recognised as Augusti in 309. However, four full Augusti all at odds with each other did not bode well for the Tetrarchic system.
Between 309 and 313 most of the claimants to the imperial office died or were killed in various civil wars. Constantine forced Maximian's suicide in 310. Galerius died naturally in 311. Maxentius was defeated by Constantine at the Battle of the Milvian Bridge in 312 and subsequently killed. Maximinus committed suicide at Tarsus
in 313 after being defeated in battle by Licinius.
By 313, therefore, there remained only two emperors: Constantine in the West and Licinius in the East. The Tetrarchic system was at an end, although it took until 324 for Constantine to finally defeat Licinius, reunite the two halves of the Roman Empire and declare himself sole Augustus.
s, each of which was overseen by a praetorian prefect
and subdivided into administrative dioceses
, and often reappeared in the title of the military supra-provincial command assigned to a magister militum
.
The pre-existing notion of consortium imperii
, the sharing of imperial power, and the notion that an associate to the throne was the designated successor (possibly conflicting with the notion of hereditary claim by birth or adoption), was to reappear repeatedly.
The idea of the two halves, the East and the West, re-emerged and eventually resulted in the permanent de facto division into two separate Roman empires after the death of Theodosius I
(though it is important to remember that the Empire was never formally divided, Emperors of East and West legally ruling as one imperial college until the fall of Rome's western empire left Byzantium, the "second Rome", sole direct heir).
Roman Emperor
The Roman emperor was the ruler of the Roman State during the imperial period . The Romans had no single term for the office although at any given time, a given title was associated with the emperor...
Diocletian
Diocletian
Diocletian |latinized]] upon his accession to Diocletian . c. 22 December 244 – 3 December 311), was a Roman Emperor from 284 to 305....
in 293, marking the end of the Crisis of the Third Century
Crisis of the Third Century
The Crisis of the Third Century was a period in which the Roman Empire nearly collapsed under the combined pressures of invasion, civil war, plague, and economic depression...
and the recovery of the Roman Empire
Roman Empire
The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....
. This Tetrarchy lasted until c.313, when internecine conflict eliminated most of the claimants to power, leaving Constantine
Constantine I
Constantine the Great , also known as Constantine I or Saint Constantine, was Roman Emperor from 306 to 337. Well known for being the first Roman emperor to convert to Christianity, Constantine and co-Emperor Licinius issued the Edict of Milan in 313, which proclaimed religious tolerance of all...
in the West and Licinius
Licinius
Licinius I , was Roman Emperor from 308 to 324. Co-author of the Edict of Milan that granted official toleration to Christians in the Roman Empire, for the majority of his reign he was the rival of Constantine I...
in the East.
Terminology
Although the term "tetrarch" was current in antiquity, it was never used to describe the imperial college under Diocletian or Galerius. The term was used to describe independent portions of a kingdom that were ruled under separate leaders. The tetrarchy of JudaeaTetrarchy (Judea)
The Tetrarchy of Judea was formed following the death of Herod the Great in 4 BCE, when his kingdom was divided between his sons as an inheritance...
, established after the death of Herod the Great
Herod the Great
Herod , also known as Herod the Great , was a Roman client king of Judea. His epithet of "the Great" is widely disputed as he is described as "a madman who murdered his own family and a great many rabbis." He is also known for his colossal building projects in Jerusalem and elsewhere, including his...
, is the most famous example of the antique tetrarchy. The term was understood in the Latin world as well, where Pliny the Elder
Pliny the Elder
Gaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...
glossed it as follows: "each is the equivalent of a kingdom, and also part of one" (regnorum instar singulae et in regna contribuuntur).
The sense in which the term was used by the ancients is distinct from the sense it carries in modern literature on Diocletianic government: whereas the Judaean tetrarchy was a set of four independent and distinct states, where each tetrarch ruled a quarter of a kingdom, the Diocletianic tetrarchy was a college, led by a single supreme leader. When later authors described the period, this is what they emphasized: Ammianus
Ammianus Marcellinus
Ammianus Marcellinus was a fourth-century Roman historian. He wrote the penultimate major historical account surviving from Antiquity...
has Constantius II admonish Julian for disobedience by appealing to the example in submission set by Diocletian's lesser colleagues; Julian himself would compare the Diocletianic tetrarchs to a chorus surrounding a leader, speaking in unison under his command. Only Lactantius
Lactantius
Lucius Caecilius Firmianus Lactantius was an early Christian author who became an advisor to the first Christian Roman emperor, Constantine I, guiding his religious policy as it developed, and tutor to his son.-Biography:...
, a contemporary of Diocletian and a deep ideological opponent of the Diocletianic state, referred to the tetrarchs as a simple multiplicity of rulers.
Much modern scholarship was written without the term. Although Edward Gibbon
Edward Gibbon
Edward Gibbon was an English historian and Member of Parliament...
pioneered the description of the Diocletianic government as a "new empire", he never used the term. Neither did Theodor Mommsen
Theodor Mommsen
Christian Matthias Theodor Mommsen was a German classical scholar, historian, jurist, journalist, politician, archaeologist, and writer generally regarded as the greatest classicist of the 19th century. His work regarding Roman history is still of fundamental importance for contemporary research...
. It did not appear in the literature until 1887, when it was used by the schoolmaster Hermann Schiller in a two-volume handbook on the Roman Empire, Geschichte der Römischen Kaiserzeit. Schiller called it "die diokletianische Tetrarchie". The term did not catch on in the literature, however, until Otto Seeck
Otto Seeck
Otto Seeck was a German classical historian who is perhaps best known for his work on the decline of the ancient world. He was born in Riga....
used it in 1897.
Creation
The first phase, sometimes referred to as the DiarchyDiarchy
Diarchy , from the Greek δι- "twice" and αρχια, "rule", is a form of government in which two individuals, the diarchs, are the heads of state. In most diarchies, the diarchs hold their position for life and pass the responsibilities and power of the position to their children or family when they...
("rule of two"), involved the designation of the general Maximian
Maximian
Maximian was Roman Emperor from 286 to 305. He was Caesar from 285 to 286, then Augustus from 286 to 305. He shared the latter title with his co-emperor and superior, Diocletian, whose political brain complemented Maximian's military brawn. Maximian established his residence at Trier but spent...
as co-emperor — firstly as Caesar
Caesar (title)
Caesar is a title of imperial character. It derives from the cognomen of Julius Caesar, the Roman dictator...
(junior emperor) in 285, followed by his promotion to Augustus
Augustus (honorific)
Augustus , Latin for "majestic," "the increaser," or "venerable", was an Ancient Roman title, which was first held by Gaius Julius Caesar Augustus , and subsequently came to be considered one of the titles of what are now known as the Roman Emperors...
in 286. Diocletian
Diocletian
Diocletian |latinized]] upon his accession to Diocletian . c. 22 December 244 – 3 December 311), was a Roman Emperor from 284 to 305....
took care of matters in the Eastern regions of the Empire while Maximian similarly took charge of the Western regions. In 293, feeling more focus was needed on both civic and military problems, Diocletian, with Maximian's consent, expanded the imperial college by appointing two Caesars (one responsible to each Augustus) — Galerius
Galerius
Galerius , was Roman Emperor from 305 to 311. During his reign he campaigned, aided by Diocletian, against the Sassanid Empire, sacking their capital Ctesiphon in 299. He also campaigned across the Danube against the Carpi, defeating them in 297 and 300...
and Constantius Chlorus
Constantius Chlorus
Constantius I , commonly known as Constantius Chlorus, was Roman Emperor from 293 to 306. He was the father of Constantine the Great and founder of the Constantinian dynasty. As Caesar he defeated the usurper Allectus in Britain and campaigned extensively along the Rhine frontier, defeating the...
.
In 305, the senior emperors jointly abdicated and retired, allowing Constantius and Galerius to be elevated in rank to Augusti. They in turn appointed two new Caesars — Severus II
Flavius Valerius Severus
Severus , sometimes known as Severus II, was a Western Roman Emperor from 306 to 307.- Officer in the Roman army :Severus was of humble birth, born in the Illyrian provinces around the middle of the third century AD...
in the east under Constantius, and Maximinus
Maximinus
Maximinus II , also known as Maximinus Daia or Maximinus Daza, was Roman Emperor from 308 to 313. He was born of Dacian peasant stock to the half sister of the emperor Galerius near their family lands around Felix Romuliana; a rural area then in the Danubian region of Moesia, now Eastern Serbia.He...
in the west under Galerius — thereby creating the second Tetrarchy.
Regions and capitals
Barbarian
Barbarian and savage are terms used to refer to a person who is perceived to be uncivilized. The word is often used either in a general reference to a member of a nation or ethnos, typically a tribal society as seen by an urban civilization either viewed as inferior, or admired as a noble savage...
s (mainly Germanic, and an endless procession from the eastern steppe; many nomadic or elsewhere chased tribes) at the Rhine and Danube. These centres are known as the "Tetrarchic capitals". Although Rome ceased to be an operational capital, the "Eternal City" continued to be nominal capital of the entire Roman Empire, not reduced to the status of a province but under its own, unique Prefect of the City (praefectus urbis, later copied in Constantinople).
The four Tetrarchic capitals were:
- NicomediaNicomediaNicomedia was an ancient city in what is now Turkey, founded in 712/11 BC as a Megarian colony and was originally known as Astacus . After being destroyed by Lysimachus, it was rebuilt by Nicomedes I of Bithynia in 264 BC under the name of Nicomedia, and has ever since been one of the most...
in northwestern Asia Minor (modern IzmitIzmitİzmit is a city in Turkey, administrative center of Kocaeli Province as well as the Kocaeli Metropolitan Municipality. It is located at the Gulf of İzmit in the Sea of Marmara, about east of Istanbul, on the northwestern part of Anatolia. The city center has a population of 294.875...
in Turkey), a base for defence against invasion from the Balkans and Persia's Sassanids was the capital of Diocletian, the eastern (and most senior) Augustus; in the final reorganisation by Constantine the Great, in 318, the equivalent of his domain, facing the most redoubtable foreign enemy, Sassanid Persia, became the pretorian prefecture Oriens 'the East', the core of later Byzantium.
- SirmiumSirmiumSirmium was a city in ancient Roman Pannonia. Firstly mentioned in the 4th century BC and originally inhabited by the Illyrians and Celts, it was conquered by the Romans in the 1st century BC and subsequently became the capital of the Roman province of Lower Pannonia. In 294 AD, Sirmium was...
(modern Sremska MitrovicaSremska MitrovicaSremska Mitrovica is a city and municipality located in the Vojvodina province of Serbia, on the left bank of the Sava river. As of 2002 the town had a total population of 39,041, while Sremska Mitrovica municipality had a population of 85,605...
) in the VojvodinaVojvodinaVojvodina, officially called Autonomous Province of Vojvodina is an autonomous province of Serbia. Its capital and largest city is Novi Sad...
region of modern SerbiaSerbiaSerbia , officially the Republic of Serbia , is a landlocked country located at the crossroads of Central and Southeast Europe, covering the southern part of the Carpathian basin and the central part of the Balkans...
, and near BelgradeBelgradeBelgrade is the capital and largest city of Serbia. It is located at the confluence of the Sava and Danube rivers, where the Pannonian Plain meets the Balkans. According to official results of Census 2011, the city has a population of 1,639,121. It is one of the 15 largest cities in Europe...
, on the DanubeDanubeThe Danube is a river in the Central Europe and the Europe's second longest river after the Volga. It is classified as an international waterway....
border) was the capital of Galerius, the eastern Caesar; this was to become the Balkans-Danube prefecture Illyricum.
- MediolanumMediolanumMediolanum, the ancient Milan, was an important Celtic and then Roman centre of northern Italy. This article charts the history of the city from its settlement by the Insubres around 600 BC, through its conquest by the Romans and its development into a key centre of Western Christianity and capital...
(modern MilanMilanMilan is the second-largest city in Italy and the capital city of the region of Lombardy and of the province of Milan. The city proper has a population of about 1.3 million, while its urban area, roughly coinciding with its administrative province and the bordering Province of Monza and Brianza ,...
, near the Alps) was the capital of Maximian, the western Augustus; his domain became "Italia et Africa", with only a short exterior border.
- Augusta Treverorum (modern TrierTrierTrier, historically called in English Treves is a city in Germany on the banks of the Moselle. It is the oldest city in Germany, founded in or before 16 BC....
, in Germany) was the capital of Constantius Chlorus, the western Caesar, near the strategic Rhine border, it had been the capital of Gallic emperor Tetricus ITetricus IGaius Pius Esuvius Tetricus was Emperor of the Gallic Empire from 271 to 274, following the murder of Victorinus. Tetricus, who ruled with his son, Tetricus II, was the last of the Gallic emperors following his surrender to the Roman emperor Aurelian.-Reign:Tetricus was a senator born to a noble...
; this quarter became the prefecture Galliae.
Aquileia
Aquileia
Aquileia is an ancient Roman city in what is now Italy, at the head of the Adriatic at the edge of the lagoons, about 10 km from the sea, on the river Natiso , the course of which has changed somewhat since Roman times...
, a port on the Adriatic coast, and Eboracum
Eboracum
Eboracum was a fort and city in Roman Britain. The settlement evolved into York, located in North Yorkshire, England.-Etymology:The first known recorded mention of Eboracum by name is dated circa 95-104 AD and is an address containing the Latin form of the settlement's name, "Eburaci", on a wooden...
(modern York
York
York is a walled city, situated at the confluence of the Rivers Ouse and Foss in North Yorkshire, England. The city has a rich heritage and has provided the backdrop to major political events throughout much of its two millennia of existence...
, in northern England near the Celtic tribes of modern Scotland and Ireland), were also significant centres for Maximian and Constantius respectively.
In terms of regional jurisdiction there was no precise division between the four Tetrarchs, and this period did not see the Roman state actually split up into four distinct sub-empires. Each emperor had his zone of influence within the Roman Empire, but little more, mainly high command in a 'war theatre'. Each Tetrarch was himself often in the field, while delegating most of the administration to the hierarchic bureaucracy headed by his respective Pretorian Prefect, each supervising several Vicarii, the governors-general in charge of another, lasting new administrative level, the civil diocese
Roman diocese
A Roman or civil diocese was one of the administrative divisions of the later Roman Empire, starting with the Tetrarchy. It formed the intermediate level of government, grouping several provinces and being in turn subordinated to a praetorian prefecture....
. For a listing of the provinces, now known as eparchy
Eparchy
Eparchy is an anglicized Greek word , authentically Latinized as eparchia and loosely translating as 'rule over something,' like province, prefecture, or territory, to have the jurisdiction over, it has specific meanings both in politics, history and in the hierarchy of the Eastern Christian...
, within each quarter (known as a praetorian prefecture), see Roman province
Roman province
In Ancient Rome, a province was the basic, and, until the Tetrarchy , largest territorial and administrative unit of the empire's territorial possessions outside of Italy...
.
In the West, the Augustus Maximian controlled the provinces west of the Adriatic Sea and the Syrtis, and within that region his Caesar, Constantius, controlled Gaul and Britain. In the East, the arrangements between the Augustus Diocletian and his Caesar, Galerius, were much more flexible.
However, it appears that some contemporary and later writers, such as the Christian author Lactantius
Lactantius
Lucius Caecilius Firmianus Lactantius was an early Christian author who became an advisor to the first Christian Roman emperor, Constantine I, guiding his religious policy as it developed, and tutor to his son.-Biography:...
, and Sextus Aurelius Victor (who wrote about fifty years later and from uncertain sources), misunderstood the Tetrarchic system in this respect, believing it to have involved a stricter division of territories between the four emperors.
Public image
Although power was shared in the Tetrarchic system, the public image of the four emperors in the imperial college was carefully managed to give the appearance of a united empire (patrimonium indivisum). This was especially important after the civil war of the third century.The Tetrarchs appeared identical in all official portraits. Coinage dating from the Tetrarchic period depicts every emperor with identical features — only the inscriptions on the coins indicate which one of the four emperors is being shown. The Byzantine sculpture Portrait of the Four Tetrarchs (pictured at right) shows the Tetrarchs again with identical features and wearing the same military costume.
Military successes
One of the greatest problems facing emperors in the Third Century Crisis was that they were only ever able to personally command troops on one front at any one time. While AurelianAurelian
Aurelian , was Roman Emperor from 270 to 275. During his reign, he defeated the Alamanni after a devastating war. He also defeated the Goths, Vandals, Juthungi, Sarmatians, and Carpi. Aurelian restored the Empire's eastern provinces after his conquest of the Palmyrene Empire in 273. The following...
and Probus were prepared to accompany their armies thousands of miles between war regions, this was not an ideal solution. Furthermore, it was risky for an emperor to delegate power in his absence to a subordinate general, who might win a victory and then be proclaimed as a rival emperor himself by his troops (which often happened). All members of the imperial college, on the other hand, were of essentially equal rank, despite two being senior emperors and two being junior; their functions and authorities were also equal.
Under the Tetrarchy a number of important military victories were secured. Both the Dyarchic and the Tetrarchic system ensured that an emperor was nearby to every crisis area to personally direct and remain in control of campaigns simultaneously on more than just one front. After suffering a defeat by the Persians in 296, Galerius crushed Narseh
Narseh
Narseh was the seventh Sassanid King of Persia , and son of Shapur I ....
in 298 — reversing a series of Roman defeats throughout the century — capturing members of the imperial household and a substantial amount of booty and gaining a highly favourable peace treaty, which secured peace between the two powers for a generation. Similarly, Constantius defeated the British usurper Allectus
Allectus
Allectus was a Roman usurper-emperor in Britain and northern Gaul from 293 to 296.-History:Allectus was treasurer to Carausius, a Menapian officer in the Roman navy who had seized power in Britain and northern Gaul in 286...
, Maximian pacified the Gauls, and Diocletian crushed the revolt of Domitianus
Domitius Domitianus
Lucius Domitius Domitianus was a Roman usurper against Diocletian, who seized power for a short time in Aegyptus.Domitianus revolted against Diocletian in 297 AD, but died in December of the same year, when Diocletian went to Aegyptus to quell with the revolt. Numismatic and papyrological evidence...
in Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
.
Demise
When in 305 the 20-year term of Diocletian and Maximian ended, both abdicated. Their Caesares, Galerius and Constantius Chlorus, were both raised to the rank of Augustus, and two new Caesares were appointed: Maximinus
Maximinus
Maximinus II , also known as Maximinus Daia or Maximinus Daza, was Roman Emperor from 308 to 313. He was born of Dacian peasant stock to the half sister of the emperor Galerius near their family lands around Felix Romuliana; a rural area then in the Danubian region of Moesia, now Eastern Serbia.He...
(Caesar to Galerius) and Flavius Valerius Severus
Flavius Valerius Severus
Severus , sometimes known as Severus II, was a Western Roman Emperor from 306 to 307.- Officer in the Roman army :Severus was of humble birth, born in the Illyrian provinces around the middle of the third century AD...
(Caesar to Constantius). These four formed the second Tetrarchy.
However, the system broke down very quickly thereafter. When Constantius died in 306, Galerius promoted Severus to Augustus while Constantine the Great was proclaimed Augustus to succeed his father Constantius, by his father's troops. At the same time, Maxentius
Maxentius
Maxentius was a Roman Emperor from 306 to 312. He was the son of former Emperor Maximian, and the son-in-law of Emperor Galerius.-Birth and early life:Maxentius' exact date of birth is unknown; it was probably around 278...
, the son of Maximian, resenting having been left out of the new arrangements, defeated Severus before forcing him to abdicate and then arranging his murder in 307. Maxentius and Maximian both then declared themselves Augusti. By 308 there were therefore no fewer than four claimants to the rank of Augustus (Galerius, Constantine, Maximian and Maxentius), and only one to that of Caesar (Maximinus).
In 308 Galerius, together with the retired emperor Diocletian and the supposedly retired Maximian, called an imperial "conference" at Carnuntum
Carnuntum
Carnuntum was a Roman army camp on the Danube in the Noricum province and after the 1st century the capital of the Upper Pannonia province...
on the River Danube. The council agreed that Licinius
Licinius
Licinius I , was Roman Emperor from 308 to 324. Co-author of the Edict of Milan that granted official toleration to Christians in the Roman Empire, for the majority of his reign he was the rival of Constantine I...
would become Augustus in the West, with Constantine as his Caesar. In the East, Galerius remained Augustus and Maximinus remained his Caesar. Maximian was to retire, and Maxentius was declared an usurper. This agreement proved disastrous: by 308 Maxentius had become de facto ruler of Italy and Africa even without any imperial rank, and neither Constantine nor Maximinus — who had both been Caesares since 306 and 305 respectively — were prepared to tolerate the promotion of the Augustus Licinius as their superior.
After an abortive attempt to placate both Constantine and Maximinus with the meaningless title filius Augusti ("son of the Augustus", essentially an alternative title for Caesar), they both had to be recognised as Augusti in 309. However, four full Augusti all at odds with each other did not bode well for the Tetrarchic system.
Between 309 and 313 most of the claimants to the imperial office died or were killed in various civil wars. Constantine forced Maximian's suicide in 310. Galerius died naturally in 311. Maxentius was defeated by Constantine at the Battle of the Milvian Bridge in 312 and subsequently killed. Maximinus committed suicide at Tarsus
Tarsus (city)
Tarsus is a historic city in south-central Turkey, 20 km inland from the Mediterranean Sea. It is part of the Adana-Mersin Metropolitan Area, the fourth-largest metropolitan area in Turkey with a population of 2.75 million...
in 313 after being defeated in battle by Licinius.
By 313, therefore, there remained only two emperors: Constantine in the West and Licinius in the East. The Tetrarchic system was at an end, although it took until 324 for Constantine to finally defeat Licinius, reunite the two halves of the Roman Empire and declare himself sole Augustus.
Timeline
293–305
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- Augusti
- Oriens DiocletianDiocletianDiocletian |latinized]] upon his accession to Diocletian . c. 22 December 244 – 3 December 311), was a Roman Emperor from 284 to 305....
(285–305) - Italia et Africa MaximianMaximianMaximian was Roman Emperor from 286 to 305. He was Caesar from 285 to 286, then Augustus from 286 to 305. He shared the latter title with his co-emperor and superior, Diocletian, whose political brain complemented Maximian's military brawn. Maximian established his residence at Trier but spent...
(285–305)
- Caesars
- Illyricum GaleriusGaleriusGalerius , was Roman Emperor from 305 to 311. During his reign he campaigned, aided by Diocletian, against the Sassanid Empire, sacking their capital Ctesiphon in 299. He also campaigned across the Danube against the Carpi, defeating them in 297 and 300...
(293–305) - Gallia et Hispaniae Constantius ChlorusConstantius ChlorusConstantius I , commonly known as Constantius Chlorus, was Roman Emperor from 293 to 306. He was the father of Constantine the Great and founder of the Constantinian dynasty. As Caesar he defeated the usurper Allectus in Britain and campaigned extensively along the Rhine frontier, defeating the...
(293–305)
- Usurpers
- Amandus et AelianusAelianus (rebel)Aelianus was together with Amandus the leader of an insurrection of Gallic peasants, called Bagaudae, in the reign of Diocletian. It was put down by the Caesar Maximianus Herculius in 285....
– leaders of the BagaudaeBagaudaeIn the time of the later Roman Empire bagaudae were groups of peasant insurgents who emerged during the "Crisis of the Third Century", and persisted particularly in the less-Romanised areas of Gallia and Hispania, where they were "exposed to the depredations of the late Roman state, and the great...
in GaulGaulGaul was a region of Western Europe during the Iron Age and Roman era, encompassing present day France, Luxembourg and Belgium, most of Switzerland, the western part of Northern Italy, as well as the parts of the Netherlands and Germany on the left bank of the Rhine. The Gauls were the speakers of...
(285–286) - Sabinus IulianusSabinus IulianusMarcus Aurelius Sabinus Iulianus was a Roman usurper against Emperor Carinus or Maximian...
– Africa Zeugitana (circa 285–293) - Britania CarausiusCarausiusMarcus Aurelius Mausaeus Valerius Carausius was a military commander of the Roman Empire in the 3rd century. He was a Menapian from Belgic Gaul, who usurped power in 286, declaring himself emperor in Britain and northern Gaul. He did this only 13 years after the Gallic Empire of the Batavian...
(286–293) - Britania AllectusAllectusAllectus was a Roman usurper-emperor in Britain and northern Gaul from 293 to 296.-History:Allectus was treasurer to Carausius, a Menapian officer in the Roman navy who had seized power in Britain and northern Gaul in 286...
(293–296) - Domitius DomitianusDomitius DomitianusLucius Domitius Domitianus was a Roman usurper against Diocletian, who seized power for a short time in Aegyptus.Domitianus revolted against Diocletian in 297 AD, but died in December of the same year, when Diocletian went to Aegyptus to quell with the revolt. Numismatic and papyrological evidence...
– AegyptusAegyptus- Aegyptus, King of Egypt and Arabia :In Greek mythology, Aegyptus is a descendant of the heifer maiden, Io, and the river-god Nilus, and was a king in Egypt. Aegyptos was the son of Belus and Achiroe, a naiad daughter of Nile. Aegyptus fathered fifty sons, who were all but one murdered by the...
(296–297) - Aurelius Achilleus – AegyptusAegyptus- Aegyptus, King of Egypt and Arabia :In Greek mythology, Aegyptus is a descendant of the heifer maiden, Io, and the river-god Nilus, and was a king in Egypt. Aegyptos was the son of Belus and Achiroe, a naiad daughter of Nile. Aegyptus fathered fifty sons, who were all but one murdered by the...
(297–298) - EugeniusEugeniusFlavius Eugenius was an usurper in the Western Roman Empire against Emperor Theodosius I. Though himself a Christian, he was the last Emperor to support Roman polytheism.-Life:...
– Syria Coele (303/304)
305–306
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- Augusti
- Illyricum GaleriusGaleriusGalerius , was Roman Emperor from 305 to 311. During his reign he campaigned, aided by Diocletian, against the Sassanid Empire, sacking their capital Ctesiphon in 299. He also campaigned across the Danube against the Carpi, defeating them in 297 and 300...
(305–306) - Gallia, Hispaniae et Britannia Constantius ChlorusConstantius ChlorusConstantius I , commonly known as Constantius Chlorus, was Roman Emperor from 293 to 306. He was the father of Constantine the Great and founder of the Constantinian dynasty. As Caesar he defeated the usurper Allectus in Britain and campaigned extensively along the Rhine frontier, defeating the...
(305–306)
- Caesars
- Oriens Maximinus Daia (305–306)
- Italia et Africa Flavius Valerius SeverusFlavius Valerius SeverusSeverus , sometimes known as Severus II, was a Western Roman Emperor from 306 to 307.- Officer in the Roman army :Severus was of humble birth, born in the Illyrian provinces around the middle of the third century AD...
(305–306)
306–307
-
- Augusti
- Illyricum GaleriusGaleriusGalerius , was Roman Emperor from 305 to 311. During his reign he campaigned, aided by Diocletian, against the Sassanid Empire, sacking their capital Ctesiphon in 299. He also campaigned across the Danube against the Carpi, defeating them in 297 and 300...
(306–307) - Italia et Africa Flavius Valerius SeverusFlavius Valerius SeverusSeverus , sometimes known as Severus II, was a Western Roman Emperor from 306 to 307.- Officer in the Roman army :Severus was of humble birth, born in the Illyrian provinces around the middle of the third century AD...
(306–307)
- Caesars
- Oriens Maximinus Daia (306–307)
- Gallia, Hispaniae et Britannia Constantine IConstantine IConstantine the Great , also known as Constantine I or Saint Constantine, was Roman Emperor from 306 to 337. Well known for being the first Roman emperor to convert to Christianity, Constantine and co-Emperor Licinius issued the Edict of Milan in 313, which proclaimed religious tolerance of all...
(306–307) - Roma MaxentiusMaxentiusMaxentius was a Roman Emperor from 306 to 312. He was the son of former Emperor Maximian, and the son-in-law of Emperor Galerius.-Birth and early life:Maxentius' exact date of birth is unknown; it was probably around 278...
(307)
307–313
-
- Augusti
- Illyricum GaleriusGaleriusGalerius , was Roman Emperor from 305 to 311. During his reign he campaigned, aided by Diocletian, against the Sassanid Empire, sacking their capital Ctesiphon in 299. He also campaigned across the Danube against the Carpi, defeating them in 297 and 300...
(307–311) - Gallia, Hispaniae et Britannia Constantine IConstantine IConstantine the Great , also known as Constantine I or Saint Constantine, was Roman Emperor from 306 to 337. Well known for being the first Roman emperor to convert to Christianity, Constantine and co-Emperor Licinius issued the Edict of Milan in 313, which proclaimed religious tolerance of all...
(307–…) - Thracia et Pontus to Taurus LiciniusLiciniusLicinius I , was Roman Emperor from 308 to 324. Co-author of the Edict of Milan that granted official toleration to Christians in the Roman Empire, for the majority of his reign he was the rival of Constantine I...
(308–…) - Italia MaxentiusMaxentiusMaxentius was a Roman Emperor from 306 to 312. He was the son of former Emperor Maximian, and the son-in-law of Emperor Galerius.-Birth and early life:Maxentius' exact date of birth is unknown; it was probably around 278...
(307–312) - Oriens from Taurus to Aegyptus Maximinus Daia (310–313)
- Italia MaximianMaximianMaximian was Roman Emperor from 286 to 305. He was Caesar from 285 to 286, then Augustus from 286 to 305. He shared the latter title with his co-emperor and superior, Diocletian, whose political brain complemented Maximian's military brawn. Maximian established his residence at Trier but spent...
(307–310)
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- Caesars
- Oriens from Taurus to Aegyptus Maximinus Daia (307–310)
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- Usurpers
- Domitius AlexanderDomitius AlexanderLucius Domitius Alexander , probably born in Phrygia, was vicarius of Africa when Emperor Maxentius ordered him to send his son as hostage to Rome. Alexander refused and proclaimed himself emperor in 308....
– AfricaAfricaAfrica is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
(308–311) Constantine's Allied
313–324
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- Augusti
- Oriens LiciniusLiciniusLicinius I , was Roman Emperor from 308 to 324. Co-author of the Edict of Milan that granted official toleration to Christians in the Roman Empire, for the majority of his reign he was the rival of Constantine I...
(313–324) - Occidens Constantine IConstantine IConstantine the Great , also known as Constantine I or Saint Constantine, was Roman Emperor from 306 to 337. Well known for being the first Roman emperor to convert to Christianity, Constantine and co-Emperor Licinius issued the Edict of Milan in 313, which proclaimed religious tolerance of all...
(313–324) - Oriens Sextus MartinianusSextus MartinianusSextus Marcius Martinianus was Roman Emperor from July to September 18, 324. He had been appointed co-emperor by Licinius.-Elevation:...
(324)
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- Caesars
- Italia BassianusBassianus (senator)- Biography :In 315 Constantine I went to Italy, where he married his sister Anastasia. The choice of Bassianus is probably to be understood in light of the fact that Bassianus' brother, Senecio, was a high official in service of Licinius, Constantine's colleague in the East, and thus this...
(313–314) - Illyricum Valerius ValensValerius ValensAurelius Valerius Valens was Roman Emperor from late 316 to March 1, 317. Valens had previously been dux limitis in Dacia, but this is all we know of him....
(314–316) - Oriens Licinius the Younger (317–324)
- Occidens CrispusCrispusFlavius Julius Crispus , also known as Flavius Claudius Crispus and Flavius Valerius Crispus, was a Caesar of the Roman Empire. He was the first-born son of Constantine I and Minervina.-Birth:...
(317–326)
Legacy
Although the Tetrarchic system as such only lasted until c. 313, many aspects survived. The fourfold regional division of the empire continued in the form of Praetorian prefecturePraetorian prefecture
The praetorian prefecture was the largest administrative division of the late Roman Empire, above the mid-level dioceses and the low-level provinces. Praetorian prefectures originated in the reign of Constantine I The praetorian prefecture was the largest administrative division of the late Roman...
s, each of which was overseen by a praetorian prefect
Praetorian prefect
Praetorian prefect was the title of a high office in the Roman Empire. Originating as the commander of the Praetorian Guard, the office gradually acquired extensive legal and administrative functions, with its holders becoming the Emperor's chief aides...
and subdivided into administrative dioceses
Roman diocese
A Roman or civil diocese was one of the administrative divisions of the later Roman Empire, starting with the Tetrarchy. It formed the intermediate level of government, grouping several provinces and being in turn subordinated to a praetorian prefecture....
, and often reappeared in the title of the military supra-provincial command assigned to a magister militum
Magister militum
Magister militum was a top-level military command used in the later Roman Empire, dating from the reign of Constantine. Used alone, the term referred to the senior military officer of the Empire...
.
The pre-existing notion of consortium imperii
Consortium imperii
Consortium imperii is a Latin term dating from the Roman Dominate, denoting the sharing of imperial authority between two or more emperors, each hence designated as consors imperii, i.e. "partner in imperium", either as formal equals or in subordination; the junior is then often the senior's...
, the sharing of imperial power, and the notion that an associate to the throne was the designated successor (possibly conflicting with the notion of hereditary claim by birth or adoption), was to reappear repeatedly.
The idea of the two halves, the East and the West, re-emerged and eventually resulted in the permanent de facto division into two separate Roman empires after the death of Theodosius I
Theodosius I
Theodosius I , also known as Theodosius the Great, was Roman Emperor from 379 to 395. Theodosius was the last emperor to rule over both the eastern and the western halves of the Roman Empire. During his reign, the Goths secured control of Illyricum after the Gothic War, establishing their homeland...
(though it is important to remember that the Empire was never formally divided, Emperors of East and West legally ruling as one imperial college until the fall of Rome's western empire left Byzantium, the "second Rome", sole direct heir).
Other examples
- Tetrarchies in the ancient world existed in both ThessalyThessalyThessaly is a traditional geographical region and an administrative region of Greece, comprising most of the ancient region of the same name. Before the Greek Dark Ages, Thessaly was known as Aeolia, and appears thus in Homer's Odyssey....
(in northern Greece) and GalatiaGalatiaAncient Galatia was an area in the highlands of central Anatolia in modern Turkey. Galatia was named for the immigrant Gauls from Thrace , who settled here and became its ruling caste in the 3rd century BC, following the Gallic invasion of the Balkans in 279 BC. It has been called the "Gallia" of...
(in central Asia MinorAsia MinorAsia Minor is a geographical location at the westernmost protrusion of Asia, also called Anatolia, and corresponds to the western two thirds of the Asian part of Turkey...
; including LycaoniaLycaoniaIn ancient geography, Lycaonia was a large region in the interior of Asia Minor, north of Mount Taurus. It was bounded on the east by Cappadocia, on the north by Galatia, on the west by Phrygia and Pisidia, while to the south it extended to the chain of Mount Taurus, where it bordered on the...
) as well as among the British CantiaciCantiaciThe Cantiaci or Cantii were a Celtic people living in Britain before the Roman conquest, and gave their name to a civitas of Roman Britain. They lived in the area now called Kent, in south-eastern England...
. - The constellation of Jewish principalities in Roman Palestine was known as a tetrarchy; see Tetrarchy (Judea)Tetrarchy (Judea)The Tetrarchy of Judea was formed following the death of Herod the Great in 4 BCE, when his kingdom was divided between his sons as an inheritance...
.