Abridged History of Rome - PART I - XI - FROM DIOCLETIAN TO CONSTANTINE

  - Ancient Rome
  (left to right: Emperor Marcus Aurelius, Pope Innocent III and Pope Sixtus IV)

XI - From Diocletian to Constantine

In this page:
Diocletian
The Tetrarchy
Maxentius
Battle of Ponte Milvio
Constantine
Constantinopolis
Iconography

Diocletian

In late 282 Emperor Probus was killed at the instigation of Marcus Aurelius Carus, his praetorian prefect. The latter died in the following year while campaigning against the Sassanids and was succeeded by his two young sons Carinus and Numerian. In November 284 Numerian fell ill in Syria and died in rather obscure circumstances. Diocles, the head of the imperial bodyguard, accused the prefect of the Praetorian guard of having poisoned the emperor and killed him. Diocles was acclaimed emperor by the army and he took the more Latin name of Diocletianus (Diocletian). Carinus, the brother of Numerian, was defeated in the following year by Diocletian, who thus became the sole ruler.
The new emperor was aware of the weakness of his position: in the previous fifty years many emperors had been overturned after just a few years or even months of reign. Diocletian appointed as co-emperor (Augustus) Maximian, a general with a large support in the army, thus enlarging the base of his power. When Maximian was made co-emperor by Diocletian, he received the appellation of Herculius, whereas Diocletian adopted that of Iovius to indicate his greater importance.
Diocletian chose to reside at Nicomedia (today's Izmit), a town near the Bosporus, from which he could closely follow and react to developments on the Danube and Persian borders and in Egypt, a country which was shattered by religion driven revolts. Maximian took responsibility for the western part of the empire and he usually resided in Milan, in Northern Italy. Rome was no longer the residence of the emperors and its Senate had less and less say in state affairs.

Milan: a section of the walls built by Maximian, now inside the Archaeological Museum

Diocletian ruled for twenty years and he introduced radical reforms which had a lasting impact so that historians set at his time the beginning of the Late Empire, the last phase of the Roman Empire.
Slaves were the main energy source of the Ancient World: the economy of Athens, the birthplace of democracy, was supported by the work of 20,000 slaves in the silver mines of nearby Lavrio. The procession of slaves behind the chariot of a pharaoh or a consul meant good news for the economy and the expansionistic policies pursued by all the ancient empires were very much dictated by the need to acquire unpaid labour.
Diocletian realized that the Roman Empire had no longer the strength to conquer other nations; most of the slaves (or their descendants) had become freemen, although very often they had continued to work for their previous owners: because of repeated economic crises which had hit the empire in the IIIrd century many small farmers had been forced to sell their land: the agriculture had become based on latifundia, very large estates owned by a few families, which employed former slaves and former small farmers. Diocletian, by a mixture of fiscal and civil laws, laid the groundwork for the development of serfage, the feudal system where agricultural labourers were tied to working on their lord's estate.
The empire security had been based for centuries on the defence of its borders; Diocletian changed this strategy by reducing the troops along the border and by stationing some legions at a certain distance from it with the aim of creating a sort of task force which would intervene when circumstances required it. This new approach required a larger army and this increased the tax burden, so that Diocletian had to complete his reforms by developing a new monetary and fiscal system. He tried to stop inflation by fixing maximum prices for many commodities throughout the whole empire.
All these changes led to some reactions, but overall the stability of the empire brought about a period of economic development.

Terme di Diocleziano: (left) central hall (now part of S. Maria degli Angeli); (right) circular hall used as a granary by the popes

Diocletian is remembered in Rome by the large baths built during his reign: as a matter of fact they were built by Maximian and dedicated to Diocletian, who visited Rome only once. They were larger than Caracalla's ones and so soundly built that most of their halls still stand. Through the centuries these halls have housed churches and granaries and more recently the collections of Museo Nazionale Romano. Diocletian rebuilt Curia Julia, the hall of the Senate which had been destroyed by fire in 283.

The Tetrarchy

Diocletian tackled the issue of ensuring an orderly transition of power at the emperor's death by convincing Maximian that they should appoint their successors choosing them outside their family circle and that they should allow them to train for their future responsibilities by exercising power on a part of the empire. In Diocletian's mind the empire was to be ruled by an imperial family composed by two Augusti and by two Caesares. Every ten years the two Augusti would abdicate and be replaced by the two Caesares who in turn would nominate two other Caesares.
This system was called Tetrarchy (four rulers) and it was first implemented in 293 when Diocletian chose as his Caesar Galerius Maximianus, (who married Valeria, Diocletian's daughter) and Maximian chose as his Caesar Gaius Flavius Valerius Constantius (known as Chlorus, the Pale, due to the whiteness of his face) who had married Maximian's stepdaughter, after having renounced his first wife Helena. Constantius Chlorus was in charge of defending Gaul and of recapturing Britain, where a split-away Empire had been established in 286 by Carausius, the commander of the fleet in charge of protecting the Roman towns on both sides of the Channel.

Arch of Galerius at Thessalonica which celebrates Galerius' victories against the Sassanids in 296-299: relief portraying the Tetrarchs: the "Augusti" are seated and the "Caesares" stand by their side

This reform of the government structure which split the empire into four areas was accompanied by an overall redesign of the empire territory which was divided into twelve dioceses, which in turn were divided into smaller partitions (provinces). This pyramidal structure anticipated that known as the feudal system. In the process some areas along the external border were abandoned e.g. parts of Morocco and others were better protected by the construction of a limes, a defence line, e.g. in Arabia Petraea (Jordan). Diocletian introduced an elaborate ceremonial which was to be strictly followed by those who were admitted to his presence; they had to kneel down and kiss the lower part of his dress: they were not allowed to raise their eyes on the emperor who claimed to be a reincarnation of Jupiter.
Diocletian was eventually forced to persecute those who refused to consider the emperor as a divine monarch. In 296 he issued a decree against the Manichaeans, the believers in a faith of Persian origin, resulting in numerous martyrs in Egypt and North Africa. Manichaeism was based on radical dualism between Good and Evil and it did not assign any role to the emperor. In 303 a similar decree was issued against the Christians and again the persecution was particularly cruel in Egypt, to the point that the Coptic (Egyptian) calendar counts the years from Diocletian's accession to the throne.

Detail of the Arch of the Tetrarchy at Sufetula

DDD . . . N . ER . . VIS . IMP .PE.
INVICTIS . AVG . ITEMQVE . CONSTANTIO . MAXIMIANO . . .
LISSIMIS . CAESARIBVS . DN . . . AVGVSTO.
ISTIC . IN . PROVINCIA . SVA . M . TVTOS
is the inscription copied by Bruce.
Travels in the footsteps of Bruce in Algeria and Tunis, by R. L. Playfair - 1877
The arch was erected to celebrate the victorious 297-298 campaigns of Maximian against the Saharan tribes who raided the Roman provinces. The names of Diocletian and Maximian, the Augusti, were deleted, whereas those of Galerius Maximianus and Gaius Constantius, the Caesares, were left untouched. Notwithstanding the length of their rule we have very few portraits and celebrative inscriptions of Diocletian and Maximian (see a dedication to Diocletian at Ephesus and a head of Maximian at Toulouse).
While Diocletian, that author of ill, and deviser of misery, was ruining all things, he could not withhold his insults, not even against God. This man, by avarice partly, and partly by timid counsels, overturned the Roman empire. (..) What was the character of his brother in empire, Maximian, called Herculius? Not unlike to that of Diocletian; and, indeed, to render their friendship so close and faithful as it was, there must have been in them a sameness of inclinations and purposes, a corresponding will and unanimity in judgment.
Lactantius, a Christian philosopher - Of the Manner in Which the Persecutors Died - ca 316

Foro Romano (near the Rostra): base of a column erected to celebrate the 10th anniversary of the Tetrarchy; one of its reliefs depicts a "suovetaurilia", a sacrifice ceremony which was already represented on a larger scale in Plutei di Traiano, another monument of the Forum

In 303 Maximian, who had jurisdiction over Rome, erected in the Forum five columns to celebrate the tenth anniversary of the Tetrarchy: four columns were dedicated to the tetrarchs and the fifth to Jupiter. The reliefs of the only remaining base of the columns show a poor quality, a clear sign that the prolonged lack of commissions due to the absence of the emperor had had a negative impact on the availability of talented sculptors in Rome.

Maxentius

In 305 Diocletian convinced Maximian that it was time for them to abdicate: Galerius and Constantius Chlorus became the new Augusti and they chose as Caesares two other generals: Severus and Maximinus. Diocletian retired to a grand palace he had built near Salona, his hometown on the coast of Dalmatia, a lovely location remote from the main political centres of the Empire; Maximian chose instead to live in Southern Italy.

Spalatum (Split): detail of the Golden Gate of the Palace of Diocletian; the two niches at the side of the gate most likely housed statues of Diocletian and Maximian

Diocletian had in mind the adoption process which had granted the prosperity of the empire from Nerva to Marcus Aurelius and he forced the other tetrarchs not to nominate their own sons as successors. The system he had devised worked as planned and the new Tetrarchy was accepted by the army. There were however two men who felt the system was depriving them of their rights: Maxentius, son of Maximian, and Flavius Constantinus (aka Constantine), son of Constantius Chlorus.
In 306 Constantius died at Eboracum (York) and the troops that same day proclaimed Constantine Augustus; Galerius, the other Augustus tried to reach an accommodation and forced Severus to appoint Constantine as his Caesar. Galerius thought in this way to save the Tetrarchy, but just a few weeks later in Rome Maxentius, supported by the praetorians and by his father claimed for himself the title of Augustus.
Severus tried to restore his authority in Rome, but his troops deserted; he surrendered himself to the rebels and in 307 he was killed. At this point Maximian made an attempt to return on the scene with the support of Constantine, who was his son-in-law, and against his own son.
In 308 Diocletian convened a sort of conference at Carnuntum (near Vienna), at the end of which Constantine was confirmed Caesar and a new man, Licinius, replaced Severus in the role of Augustus.
In 310 at Arelate (Arles), during an absence of Constantine, Maximian announced that his son-in-law had died fighting the Franks, but the troops remained loyal to their commanders and after Constantine returned to Arelate he was forced to commit suicide.
Maxentius was never recognized either as Caesar or as Augustus and the tetrarchs regarded him as an usurper; however they did not move to crush his rebellion and for some years he ruled over Rome and parts of Italy and the province of Africa.

Tempio di Romolo: detail of the entrance

Maxentius tried to acquire legitimacy by emphasizing the ancient role of Rome: he built a new temple (dedicated to his deceased son Romulus) and a large basilica in the Forum and even a new circus near Via Appia. The decoration of these buildings was to some extent taken from other monuments: an obelisk was moved from the city to the circus. The fine portal of the temple to Romulus is most likely a work of the previous centuries, but the use of porphyry as a symbol of the imperial power began in this period.

Battle of Ponte Milvio

In April 311 Galerius put an end to the persecution of the Christians and declared religio lecita (legitimate religion) their faith. A few days later he died: relations among the remaining three tetrarchs were very tense: Constantine controlled the western part of the empire with the exception of most of Italy, while Licinius and Maximinus ruled over its eastern part.
Constantine thought the time had come to move against his brother-in-law Maxentius. He laid siege to Verona, which was loyal to Maxentius and, after having conquered this fortified town, he descended the Italian peninsula towards Rome. Maxentius had strengthened the walls of Rome, but nevertheless he decided not to wait for Constantine to lay siege to the city and the two armies engaged on the Via Flaminia, north of Rome. After the first unfavourable skirmishes Maxentius tried to retreat to Rome, but he had to manoeuvre in a narrow space because Via Flaminia is flanked by the Tiber on one side and by hills on the other. The retreat became a rout at Ponte Milvio and Maxentius fell into the river and drowned.

Arco di Costantino: (above) battle of Ponte Milvio; (below) siege of Verona

In 315 an arch was erected by the Roman Senate to celebrate Constantine: its decoration was mainly composed of reliefs taken from monuments to Trajan, Hadrian and Marcus Aurelius, but six reliefs portrayed the victorious campaign of Constantine against Maxentius. The inscription of the arch makes reference to a divine inspiration (ISTINCTU DIVINITATIS) which helped Constantine.
According to the Christian tradition, before the battle Constantine had the vision of a cross accompanied by a cloth with the words EN TOUTOI NIKA (Greek) - IN HOC SIGNO VINCES (Latin) (with this symbol you will win) and he placed a cross and Christ's monogram on his war emblems. The relief portraying the battle of Ponte Milvio is damaged: a flying character can maybe seen in its left side: this character (an angel or more likely a personification of Victory) is very clearly visible in the relief showing the siege of Verona.
It is interesting to note that the troops of Maxentius were represented wearing the uniform which (in Trajan's Column) identified the Sarmatians, a tribe living in southern Russia: the Senate chose to ignore that the battle of Ponte Milvio had been fought during a civil war, and not in a campaign against the external enemies of the Empire. In the lower relief Constantine appears to the right of the angel: his size is much larger than that of the other figures.
The image used as a background for this page shows a detail of Constantine's Vision by Gian Lorenzo Bernini.

Constantine

Italians have a saying (parenti/serpenti - relatives/snakes) to mean that often the worst conflicts develop within a family; in 313 a row broke out in the imperial family designed by Diocletian: Licinius defeated Maximinus and became the sole ruler of the eastern part of the empire. He and Constantine met that same year in Milan where they jointly issued the Edict of Tolerance, by which they granted all citizens freedom in the exercise of religion. Constantine ruled over the western part of the empire where the ancient religion and the more modern faiths in Mithra and Sol Invictus were still prevailing; by this edict he thought to gain the favour of Licinius' subjects, many of whom had embraced the Christian faith.

British Museum: (left) silver bowl celebrating the tenth anniversary of Licinius' rule and wishing him ten other years "Sic X, sic XX"; (right) jewel incorporating a "solidus", a golden coin introduced by Constantine

The two Augusti did not trust each other and in the following years they had repeated clashes. However it was only in 324 that their confrontation evolved into open war.
Constantine defeated Licinius at Adrianopolis (today's Edirne in European Turkey) forcing him to retreat to Byzantium. Crispus, Constantine's eldest son and Caesar, blocked the city by sea, while a storm destroyed Licinius' fleet. Eventually Licinius surrendered and abdicated: he was initially treated as a sort of pensioner, but one year later he was executed. Constantine became the sole ruler of the empire.

(left/centre) Foro Romano near Arco di Settimio Severo: bases of statues dedicated to Maxentius and Constantine; (right) statue of Constantine in Piazza del Campidoglio

TEXT OF THE INSCRIPTIONS

MARTI INVICTO PATRI ET AETERNAE URBIS SUAE CONDITORIBUS DOMINUS NOSTER IMP(erator) MAXENTIUS P(ius) F(elix)(*) INVICTUS AUG(ustus) (*) erased line

DOMINO NOSTRO CONSTANTINO PIO FELICI INVICTO ET BEATISSIMO SEMPER AUGUSTO FILIO DIVI PII CONSTANTI AUGUSTI

Constantine spent most of his life away from Rome, especially at Augusta Treverorum (Trier) where he could rely on the support of his legionaries and where he built palaces and baths and he entertained his subjects with an exhibition, which consisted in exposing many thousand unarmed Frankish prisoners to be torn in pieces by wild beasts.
The government of Rome was entrusted to a Praefectus Urbi who was responsible also for the maintenance of the imperial palaces. Many inscriptions and honorary columns dedicated to Constantine and other members of his family are "signed" by this high officer. It is interesting to highlight the use of new terms to define the emperor. While the first emperors were divinized only after their death, Diocletian required to be called dominus and deus (Lord and God) and the word dominus in particular was frequently associated with the following emperors. Maxentius used it in an altar dedicated to Mars, while the Praefectus Urbi used it with reference to Constantine.
In addition to the arch in the centre of Rome the victory of Constantine was celebrated by another arch along Via Flaminia. Constantine built new baths on the Quirinale hill; they were decorated with statues and reliefs taken from other monuments, with the exception of statues of Constantine and his son by the same name. The sculptor portrayed them in the typical attire and posture of many other previous emperors, but the face is void of expression: the naturalistic approach of classical art was gradually being replaced by a symbolic one as shown in gigantic marble and bronze statues of Constantine. An equestrian bronze statue of Marcus Aurelius in Rome was assumed to represent Constantine and it was not melted.

Constantinopolis

In 330 Constantine renamed with his name the city of Byzantium where he had defeated Licinius. The monuments he built in Constantinople reflect the ambiguity of the Emperor's religious politics. He incorporated an existing temple of Castor and Pollux - both closely linked to horses - into the hippodrome, he built a temple to Tyche, a goddess who was patron of towns and wore a crown resembling their walls, and he placed at the top of a column a statue of himself wearing the symbols of Sol Invictus (Unconquered/ Invincible Sun), a deity who was very popular among his troops. At the same time he allowed the Christian community to build large churches, in one of which (Aghia Apostoli - Holy Apostles - lost) he was eventually buried in a porphyry sarcophagus.
He built an imperial palace which was not just a residence, but housed the large court which presided over the administration of the empire.
Constantine played a significant role in trying to iron out the growing differences among the Christians. The main contrast revolved around the figure of Jesus who, according to the Egyptian theologian Arius, was subordinate to God the Father. This view was challenged by other bishops and eventually an ecumenical council (meeting of all bishops) was convened at Nicaea. The outcome of the council was a condemnation of Arianism which was regarded as heretical. The Arian Creed however continued to be preached and had a large number of followers including members of the imperial family and Ulfilas, a missionary who converted the Goths, a group of Germanic tribes living beyond the Danube.

Walls surrounding the Mausoleum of Costanza, Constantine's daughter

The Edict of Tolerance allowed the Christians living in Rome to build their first large churches: the traditional layout of the pagan temple was abandoned both because it did not suit the Christian ceremonies and to mark a difference from the old beliefs. The oldest churches of Rome had the rectangular shape of the Roman basilicas and they were built on the tombs of saints and martyrs, which were located outside the walls: this was the origin of S. Pietro, S. Paolo, S. Agnese and S. Lorenzo.
Owing mainly to the initiatives of Helena, Constantine's mother, who had converted to the Christian faith, other basilicas were built within the walls near her palace: S. Giovanni in Laterano and S. Croce in Gerusalemme. All these early basilicas were replaced by other buildings or were greatly modified in the following centuries.
Helena is thought to have been buried in a large round mausoleum along Via Labicana. She is venerated as a saint for having found the True Cross at Jerusalem. See her statue by Andrea Bolgi in S. Pietro and the Stories of the True Cross by Piero della Francesca at Arezzo.

Musei Capitolini: "Tensa Capitolina", a ceremonial cart (see it in a IVth century "opus sectile" panel from the Basilica di Giunio Basso); its fragments were found in the environs of Rome in 1872; it is dated 325-350 AD; its decoration is mainly based on bronze bands depicting events of the life of Achilles which indicates that the traditional myths were still in fashion at the time. You may wish to see another ceremonial cart which was found in 2021 at Pompeii

Constantine was the first Christian emperor, a glory which has served to cover a multitude of sins: it is indeed impossible to forget that he was the chosen instrument of a great and blessed revolution, but in other respects it is as impossible to look back to the period of Constantine without horror - an era when bloodshed and barbarism, and the general depravity of morals and taste seemed to have reached their climax.
Anna Jameson - Diary of an Ennuy�e - 1826
For the Greek Orthodox Church Constantine is a saint and many paintings and statues in the churches of Rome celebrate him almost as a saint. The fact that he killed his second wife, his eldest son, his father-in-law and two of his brothers-in-law is regarded as a venial sin. See Oratorio di San Silvestro with the frescoes depicting Constantine's purported donation of the City of Rome to Pope Sylvester I.
It is fair to say that not only is the general interpretation of the age of Constantine open to debate, even today, but also almost every major event and source is the subject of scholarly controversy. The central figure of the age, the emperor Constantine, presents the first and perhaps most difficult hurdle. Much depends on the interpretation of Constantine's motives and character.
David P. Jordan - Gibbon and his Roman Empire Jordan - 1971

Iconography

The following links show works of art portraying characters and events mentioned in this page; they open in another window:
Statue of the Tetrarchs in St. Mark's - Venice.
The Battle of Ponte Milvio by Giulio Romano.
The Entry of Constantine into Rome by Peter Paul Rubens (1622).

Next page:
XII - The End of Ancient Rome