Diocletian

Diocletian
Emperor of the Roman Empire
Diocletian
Reign	November 20 284 – April 1 286 (alone) April 1 286 – May 1 305 (as Augustus of the East, with Maximian as Augustus of the West)
Predecessor	Numerian
Successor	Constantius Chlorus and Galerius
Spouse	Prisca
Issue	Valeria
Names Gaius Aurelius Valerius Diocletianus

Gaius Aurelius Valerius Diocletianus (ca. December 22 244 – December 3 311), born Diocles (Greek: Διοκλής) and known as Diocletian (/ˌdаɪəˈkliːʃən/), was Roman Emperor from November 20 284 to May 1 305. Born to a Dalmatian family of low status, he rose through the ranks of the military to become cavalry commander to the emperor Carus after 282. In the wake of a botched Persian campaign on which Carus and his son Numerian had died, Diocletian revealed and murdered the man he blamed for their deaths, and had the army hail him emperor in their stead. A brief confrontation with Carus' other surviving son Carinus at the Battle of the Margus, secured Diocletian in his role as emperor. Diocletian soon appointed fellow-officer Maximian his Augustus, his senior co-emperor, and further delegated his powers on March 1 293, appointing Galerius and Constantius as Caesars, junior co-emperors to the Augusti. Under this "Tetrarchy", or "rule of four", each emperor would rule over a quarter-division of the empire, arraigning to himself the highest legal and military authority in his alloted lands. Through personally led campaigns against Sarmatian and Danubian tribes (285–90), the Alamanni (288), and usurpers in Egypt (297–98), Diocletian secured the empire's borders and purged its insides of threats to his power. In their territories, his subordinates would do the same. In 299, Diocletian led negotiations with Sassanid Persia, the empire's traditional enemy, and achieved a lasting and favorable peace.

Diocletian's reforms of imperial administration, separating and enlarging the empire's civil and military services, introducing previously unattested offices, and re-organizing the empire's provincial divisions, established a larger and more bureaucratic government than the Roman Empire had ever seen. For the convenience of the tetrarchs, new power centers were established in Nicomedia, Mediolanum, Antioch and Trier, distant from the traditional capitol at Rome, but close to the military concerns of the empire. Developing on third-century trends towards absolutism, Diocletian increasingly styled himself an autocrat, dividing himself from the empire's masses with structured forms of court ceremonial and imposing architecture. Bureaucratic and military growth, constant campaigning, and an excess of construction projects increased the state's expenditures, and necessitated a comprehensive tax reform. From at least 297 on, imperial taxation was standardized, made more equitable, and levied at generally higher rates than before.

Not all Diocletian's plans were successful: the Edict on Maximum Prices (301), Diocletian's attempt to curb inflation via price controls, was unsuccessful, counterproductive, and quickly ignored in light of economic realities. Although effective for the period of his rule, Diocletian's tetrarchic system collapsed in his absence due to the dynastic claims Maxentius, son of Maximian, and Constantine, son of Constantius, made on the system. The Diocletianic Persecution, the empire's last systematic persecution of Christianity, failed to significantly weaken the Church. By 324, the empire would be ruled by a single Christian emperor, Constantine. In spite of his failures, Diocletian's reforms fundamentally changed the structure of Roman imperial government and helped stabilize the empire economically and militarily, enabling an empire that had seemed near the brink of collapse in Diocletian's youth to remain essentially intact for another hundred years. Weakened by illness, Diocletian left the imperial office on May 1 305. He would live out his retirement in a palace on the Dalmatian coast, personally tending to vegetable gardens.

Early life

Diocletian was probably born near Salona in Dalmatia (Solin in modern Croatia), some time around 244, perhaps on December 22. Named Diocles, potentially Diocles Valerius, the child's parents were of low status. Writers hostile to him would later claim that his father was a scribe or a freedman, or even that Diocles was a freedman himself. The first forty years of his life are mostly obscure. Zonaras mentions that he was Dux Moesiae, holding responsibility for defending the lower Danube. In 282, the legions of the upper Danube, of Raetia and Noricum, proclaimed the praetorian prefect M. Aurelius Carus as emperor, beginning a rebellion against what had been the apparently secure government of the emperor Probus. Probus' army, stationed in Sirmium (Sremska Mitrovica, Serbia), decided against fighting Carus, and assassinated Probus instead. Diocles started gaining the new emperor's trust, and soon obtained the rank of Comes domesticorum, commander of the cavalry arm of the imperial bodyguard, a unit that always attended the emperor.

Carus, already sixty, wishing to establish a dynasty, and possessing the distinct advantage of having two adult sons, immediately elevated his sons Carinus and Numerian to the rank of Caesar. In 283, Carus raised Carinus to the title Augustus, left him in charge of the care of the West, and moved with Numerian, Diocles, and the praetorian prefect Aper to the East, against the Sassanid Empire. The Sassanids had been suffering from a succession dispute since the death of Shapur, and were in no position to oppose Carus' advance. According to Zonaras, Eutropius, and Festus, Carus won a major victory against the unstable empire, taking Seleucia and the Sassanid capital of Ctesiphon (near modern Al-Mada'in, Iraq), cities on opposite banks of the Tigris. In celebration, Carus and his sons each took the title of Persici maximi in celebration, and Carus gave Numerianus the title of Augustus. Carus then died, either in July or early August, reportedly due to having been struck by lightning.

Rise to power

Death of Numerian

Map of the Roman Empire ca. 400

Carus's death left his unpopular sons Numerian and Carinus as the new Augusti. Carinus quickly made his way to Rome, arriving there by January 284, but Numerian lingered in the east. The retreat from Persia was orderly: the regnant Bahram II was still struggling to establish his authority, and left the Roman troops to withdraw unopposed. By March 284 he had only reached Emesa (Homs) in Syria; by November, only Asia Minor. In Emesa he was apparently still alive and in good health, as he issued the only extant rescript in his name while there. After his stop in Emesa, however, Numerian's staff, including the prefect Aper, began to claim that Numerian was ill, that he was suffering from an inflammation of the eyes, and had to travel in a closed coach. In Bithynia, some of Numerian's soldiers sensed a bad smell emanating from the coach. It would have been the kind of smell corpses are known to emanate in the later stages of decay, especially in hot climates. They opened its curtains. Inside, they found Numerian, dead.

Aper officially broke the news in Nicomedia (İzmit) in November. Numerianus' generals and tribunes then called a council for the succession, where they chose Diocles as emperor, despite Aper's attempts to garner their support. On November 20 284, the army of the east gathered on a hill three miles Template:Km to mi outside Nicomedia, the soldiers unanimously saluted their new Augustus. Diocles accepted the purple vestments of the emperor. He raised his sword to the light the sun, and swore upon oath that Numerian's death happened through no fault of his own: it was Aper that had both committed and concealed the emperor's assassination. In full view of the army, Diocletian drew his blade and plunged it into the helpless Aper, who died on the spot. Soon after Aper's death, Diocles changed his name to the more Latinate and grand "Diocletianus", fully Gaius Aurelius Valerius Diocletianus. This act placed Diocletian in the line of legitimate emperors succeeding Gallienus (r. 253–68).

Conflict with Carinus

Head of Carinus at the Centrale Montemartini

In a lesser ceremony following his accession, Diocletian elevated a man called Bassus to be his consular colleague. The two assumed the fasces in place of Carinus and Numerianus. Bassus was a member of a Campanian senatorial family, a man who had previously been consul, proconsul of Africa, and chosen by Probus for signal distinction; he was a man skilled in areas of government where Diocletian, presumably, had no experience. Diocletian's elevation of Bassus to consulship symbolized his rejection of Carinus' government in Rome, his refusal to accept second-tier status to any other emperor, and his willingness to continue the long-standing collaboration between senatorial and military aristocracies. It also tied his success to that of the Senate, whose support he would need in an advance on Rome.

Diocletian was not the sole challenge to Carinus' rule: at the time, the usurper M. Aurelius Julianus, Carinus' corrector Venetiae, was in control of northern Italy and Pannonia. Julianus took control in the period following Numerian's death and Diocletian's accession, printing coins from the mint at Siscia (Sisak, Croatia) establishing himself as emperor and promising freedom. It was all good press for Diocletian, aiding in his presentation of Carinus as a cruel and oppressive tyrant. Julianus' forces were weak, however, and he was handily dispersed as Carinus' armies traveled from distant Britain south through northern Italy. Diocletian, as the man to whom the eastern provinces were quickly swearing their allegiance, was clearly the much greater threat. Over the winter months, Diocletian advanced west across the Balkans. In the spring, at some time before the end of May, his armies met those of Carinus across the river Margus (Great Morava) in Moesia. In modern accounts, the site has been located between the Mons Aureus (Seone, west of Smederevo) and Viminacium, near modern Belgrade, Serbia.

Despite having the stronger army, Carinus held the weaker position. Carinus' rule was unpopular, and it is possible that Flavius Constantius, the governor of Dalmatia, had already defected to Diocletian in early spring, for he had been a companion to Diocletian in the household guard. certainly, his prefect Aristobulus defected when the battle begun. It was subsequently alleged that Carinus had not only maltreated the Senate and its associated women, but also seduced the wives of his officers. In the course of the ensuing battle, Carinus was killed by his own men, and both western and eastern armies subsequently acclaimed Diocletian emperor. Diocletian exacted an oath of allegiance from the defeated army and moved on.

Early rule

In the immediate period after his defeat of Carinus, Diocletian may have become involved in battles against the Quadi and Marcomanni, preventing him from moving on to Rome. At some time, Diocletian made his way to northern Italy and forced some changes in imperial government, but it is not known with certainty whether Diocletian visited the city of Rome in the ensuing years. There is a contemporary issue of coins that has been argued as suggestive of an imperial adventus (arrival) for the city, but some modern historians state that Diocletian avoided the city, and that he did so on principle: the city and its Senate were simply no longer politically relevant to the affairs of the empire, and its residents needed to be taught as much. Diocletian would date his reign from the date of his elevation by the army, not the date of his ratification by the Senate. If Diocletian ever did enter the city, he did not stay long; he is attested back in the Balkans by November 2 285, campaigning against the Sarmatians.

While in Italy, Diocletian solidified his rule by providing some favored individuals imperial appointments. He replaced the prefect of Rome with Bassus. Diocletian exercised clemency with those who served under Carinus and Numerianus, some of whom may have betrayed Carinus at the Margus. In an act the epitomator Aurelius Victor denotes as unusual act of clementia, he did not kill or depose Carinus' traitorous praetorian prefect and consul Ti. Claudius Aurelius Aristobulus, but instead confirmed him in both roles, and later gave him the proconsulate of Africa and the rank of urban prefect. Most officials who had served under Carinus continued their posts under Diocletian.

Maximian made co-emperor

Maximian was by all accounts a loyal man, in spite of his military and moral inadequacies. His consistent loyalty proved an important component of the tetrarchy's early successes.

Recent history had demonstrated that sole rulership was dangerous to the stability of the empire, most clearly in the ignominious terminations of Aurelian (r. 270–275) and Probus. What is more, contemporary imperial concerns stretched across the whole of the empire: conflicts had only recently arisen in every region from Gaul to Syria, from Egypt to the lower Danube. The empire was simply too much for a single administrator to control. Diocletian needed a lieutenant. At some time in 285 in Mediolanum (Milan, Italy), perhaps July 21, perhaps July 25, Diocletian proclaimed his thirty-four year old fellow-officer Maximian as his Caesar, his co-ruler.

The concept of dual rulership enshrined in Maximian's appointment was nothing new to the Roman Empire. Augustus, the first emperor (r. 27 BC–AD 19), had shared power with his colleagues, and more formal offices of co-emperor had existed from Marcus Aurelius (r. 161–180) on. Most recently, the emperor Carus and his sons supplied a model of co-rulership, albeit an unsuccessful one. But Diocletian was in a less comfortable position than most of his predecessors: he could not fall back on dynastic models, as he had a daughter, but no sons. His appointment had to be made outside of his family. It has been argued that Diocletian, like some childless appointees of co-rulers before him, declared Maximian his filius Augusti, his "Augustan son", in a form of symbolic adoption, but this argument has not been universally accepted.

The relationship was quickly couched in religious terms. Ca. 287 Diocletian assumed the title Iovius, while Maximian assumed Herculius. These titles would soon appear on their coinage. The titles were probably meant to convey certain characteristics of their associated leaders: Diocletian, in Jovian style, would take on the dominating roles of planning and commanding; Maximian, in Herculian mode, would take on the lesser, but still heroic, role of completing assigned tasks. For all their religious connotations, however, the emperors were not meant to be "gods" in the tradition of the Imperial cult—although they may have been hailed as such in Imperial panegyrics. Instead, they were seen as the representatives of the gods, as the tools effecting the gods' will on earth. The shift to divine sanctification from military acclamation took power from the hands of the army, where it had been throughout the third century, and placed it in the hands of the gods. It was this divine legitimization that came to separate Diocletian and Maximian from potential rivals, rather than mere military power or dynastic claim. In the days following their acclamation, Maximian was assigned the government of the West and dispatched to fight the rebel Bagaudae in Gaul. Diocletian returned to the East.

Conflict with Sarmatia and Persia

Diocletian progressed slowly, encountering and defeating Sarmatian raiders in the Balkans in the autumn, before November 2 285. The Sarmatians had demanded assistance from the emperor, requesting that he either help them regain territories now lost to their people, or grant them rights to pasturage within the imperial borders. Diocletian refused, and took them to battle, but, like his predecessors, was unable to eliminate them entirely. The nomadic pressures of the European Plain remained, and could not be solved by a single war; soon the Sarmatians would have to be fought again. He wintered in Nicomedia, where he is placed by a rescript of March 3 286, the following spring. There may have been a revolt in the eastern provinces at this time, because Diocletian is recorded as having brought settlers from Asia to populate emptied farmlands in Thrace. The following spring, he visited Judea, where he is attested in a rescript of May 31 287. Presumably, he returned to spend the following winter in Nicomedia. Diocletian earned some diplomatic success in the East: in 287, Bahram II, king of Persia, granted him precious gifts, declared open friendship with the empire, and invited Diocletian to visit him. Roman sources insist that the act was entirely voluntary.

At approximately the same time, Persia ceased laying claim to Armenia and recognized Roman authority over territory to the west and south of the Tigris. The western portion of Armenia was incorporated into the Roman empire and made a province. Tiridates III, Arsacid claimant to the Armenian throne and client of the Roman empire, disinherited and forced to take refuge in the Roman empire after the Persian conquest of 252/3, returned to lay claim to the eastern half of his ancestral domain. He would encounter no opposition. Bahram II's gifts were widely recognized as symbolic of a victory in the ongoing conflict with Persia, and Diocletian was hailed as the "founder of eternal peace". The events might have represented a formal end to Carus' eastern campaign, which may have ended without an acknowledged peace. At the conclusion of discussions with the Persians, the Mesopotamian frontier was re-organized, and Circesium (Buseire, Syria), a city on the Euphrates, was fortified.

Maximian made Augustus

In the West, Maximian's campaigns were not proceeding as smoothly. The Bagaudae had been easily suppressed, but the man he had put in charge of operations against Saxon and Frankish pirates on the Saxon Shore, Carausius had begun keeping the goods secured from the pirates for himself, refusing to relinquish them to either the population at large or the imperial treasury. Spurred by the crisis, on April 1 286, Maximian took up the title of Augustus. Maximian's appointment is made somewhat spectacular by the fact that it was physically impossible for Diocletian to have been on site to witness the event. It has even been suggested that Maximian usurped the title, and was only later recognized by Diocletian in hopes of avoiding civil war. Although this suggestion is unpopular, it is clear that Diocletian meant for Maximian to play his role with a certain amount of necessary independence from Diocletian.

Carausius, rebel emperor of Roman Britain. Most of the evidence for Carausius' reign comes from his coinage, which was of generally fine quality.

Following his rise to the office of Augustus, Maximian moved to confront the rebellious governor. Carausius, threatened by his advance, proclaimed himself Augustus, and spurred Britain and northwestern Gaul into open revolt against the central authorities. Maximian realized that he could not immediately suppress the rogue commander, and so, for the whole campaigning season of 287, campaigned against tribes beyond the Rhine instead. The following spring, as Maximian made preparations for dealing with Carausius, Diocletian returned from the East. Meeting at Moguntiacum (Mainz, Germany), the two emperors agreed on a joint campaign against the Alamanni. Diocletian invaded into Germania through Raetia while Maximian progressed from Mainz, each emperor burning crops and food supplies as they went, destroying the Germans' means of sustenance and denying them their rest. The two men added territory to the empire and allowed Maximian's build-up to proceed without further disturbance. On his way, Diocletian managed what was probably a rapid campaign against resurgent Sarmatians. No details survive, but surviving inscriptions indicate that Diocletian took the title Sarmaticus Maximus after the 289 campaign.

Maximian quickly lost the fleet he raised, probably in the early spring of 290. The panegyrist who refers to the loss suggests that its cause was a storm, but this might simply be the panegyrist's attempt to play down the embarrassment of defeat. Diocletian broke off a tour of the Eastern provinces soon thereafter, potentially after having received news of Maximian's failure. He might have been attempting to persuade the desert tribes in the regions between Rome and Persia to ally themselves with Rome, reviving the old, Rome-friendly, Palmyrene sphere of influence, perhaps simply to reduce the frequency of their incursions, but no details survive for these events. Some of the princes of these states were given the status of Persian client kings; a disturbing fact in light of increasing tensions with that kingdom. He returned with haste to the West, reaching Emesa by May 10 290, and Sirmium on the Danube by July 1 290.

Diocletian met Maximian in Milan in the winter of 290–1, either in late December 290 or January 291. The meeting was undertaken with a sense of solemn pageantry. Much of the emperors' time was spent making public appearances. A deputation from the Roman Senate met with the emperors, renewing that body's infrequent contact with the imperial office. The choice to avoid Rome served as a further snub to the city's necessity, a fact expressed in the panegyric detailing the events: "In consequence the capital of the Empire appeared to be there, where the two emperors met"; the implication being that the true capital of the empire is where the emperor sits. It has been surmised that the ceremonies were arranged to demonstrate Diocletian's continuing support for his faltering colleague. Some matters of politics and war were most likely made, but they were made in secret. The Augusti would not meet again until 303.

Tetrarchy

Main article: Tetrarchy

Foundation of the tetrarchy

Some time after his return, and before 293, the command of the war against Carausius was transfered from Maximian to Flavius Constantius. Constantius was a former governor of Dalmatia, Maximian's praetorian prefect in Gaul, the husband to Maximian's daughter, Theodora, and a man of military experience stretching back to Aurelian's campaigns against Zenobia (272–73). On March 1 293 at Milan, Maximian gave Constantius the office of Caesar. On either March 1 or May 21 293, in either Philippopolis (Plovdiv, Bulgaria) or Sirmium, Diocletian would do the same for one Galerius, husband to Diocletian's daughter Valeria, and perhaps Diocletian's praetorian prefect. Constantius was assigned to govern Gaul and Britain. Galerius was assigned Syria, Palestine, Egypt, and responsibility for the eastern borderlands.

With its total of four emperors, this form of government is called the tetrarchy, from a Greek term meaning "rulership by four". The tetrarchic emperors were more or less sovereign in their own lands, travelling with their own imperial courts, administrators, secretaries, and armies. The four emperors were joined by blood and marriage. Diocletian and Maximian styled themselves as brothers, and formally adopted Galerius and Constantius as sons in 293. These relationships implied a certain line of potential heirs, in which the imperial line would move through Maximian to his son Maxentius, and from Constantius to his son Constantine, by way of hereditary succession. In preparation for their future roles, both Constantine and Maxentius were taken to Diocletian's court in Nicomedia.

Conflict in the Balkans and Egypt

A Trajanic temple on the island of Philae, the newly established border between the Nobatae and Blemmyes and Roman Egypt

Diocletian spent the spring of 293 traveling with the new Caesar of the East, Galerius, from Sirmium to Byzantium (Istanbul, Turkey). Following that excursion, Diocletian returned to Sirmium, where he would remain for the following winter and spring. He campaigned again against the Sarmatians in the campaigning season of 294, probably in the autumn, winning a victory and building forts north of the Danube. The defeat was such that the Sarmatians did not trouble the Danubian provinces for a long time. The new forts at Aquincum (Budapest, Hungary), Bononia (Vidin, Bulgaria), Ulcisia Vetera, Castra Florentium, Intercisa (Dunaújváros, Hungary), and Onagrinum (Begeč, Serbia) would become part of a new defensive line called the Ripa Sarmatica. In 295 and 296, Diocletian would see further campaigning in the region. He would also win some consolidation over the Danube frontier with a victory over the Carpi in the summer of 296. By the end of his reign, Diocletian had secured the entire length of the Danube, completing it with forts, bridgeheads, highways, and walled towns, and providing fifteen or more legions to patrol the region. It came at a heavy cost, but it was a significant achievement in an area otherwise difficult to defend.

Galerius, meanwhile, was engaged in disputes in Upper Egypt for the period, and would only return to Syria in 295, just in time to meet a revanchist Persia on the march. Diocletian's attempts to bring the Egyptian tax system in line with imperial standards stirred discontent, and a revolt soon swept the region. The usurper L. Domitius Domitianus had seized authority for himself in July or August 297. Much of Egypt, including Alexandria, recognized his rule. Diocletian moved into Egypt to suppress him, first suppressing rebels in the Thebaid in the autumn of 297, then moving on to siege Alexandria. Domitianus died in December 297, by which time Diocletian had secured control of the Egyptian countryside. Alexandria, whose defense was organized under Diocletian's corrector Aurelius Achilleus, held out until a later date, probably March 298.

The following summer, Diocletian traveled south along the Nile, visiting Oxyrhynchus and Elephantine, and reaching Nubia to make peace with the Nobatae and Blemmyes. Under the terms of the peace treaty Rome's borders were moved north to Philae and the two tribes were to receive an annual gold stipend. Some bureaucratic affairs were tied up during Diocletian's stay: a census took place, and Alexandria, in punishment for its rebellion, lost the ability to mint an independent coinage. His reforms in the region, combined with those of Septimus Severus, brought Egyptian administrative practice more in line with general Roman practice than it had been at any time in its recorded history. Diocletian left Africa quickly after the event, moving from Upper Egypt in September 298 to Syria in February 299, to reconvene with Galerius, newly victorious in his campaign against Persia.

War with Persia

See also: Roman relations with the Parthians and Sassanids and Roman-Persian Wars

Invasion, counterinvasion

In 294, Narseh, a son of Shapur who had been passed over for the Sassanid succession, came into power in Persia. Narseh probably moved to eliminate Bahram III, a young man installed by a noble named Vahunam in the wake of Bahram II's death in 293. In early 294, Narseh sent Diocletian the customary package of gifts, but within Persia he was destroying every trace of his immediate predecessors, erasing their names from public monuments. He sought to identify himself with the warlike reigns of Ardashir (r. 226–41) and Shapur (r. 241–72), the same Shapur who had sacked Roman Antioch, skinned the Emperor Valerian (r. 253–260) to decorate his war temple.

In 295 or 296, Narseh declared war on Rome. He appears to have first invaded western Armenia, retaking the lands delivered to Tiridates in the peace of 287. He would occupy the lands there until the following year. Narseh then moved south into Roman Mesopotamia, where he inflicted a severe defeat on Galerius, then commander of the Eastern forces, in the region between Carrhae (Harran, Turkey) and Callinicum (Ar-Raqqah, Syria). Diocletian may or may not have been present at the battle, but would present himself soon afterwards at Antioch, where the official version of events was made clear: Galerius was to take all the blame for the affair. In Antioch, Diocletian forced Galerius to walk a mile in advance of his imperial cart while still clad in the purple robes of an emperor. Galerius' failures would not be accepted.

Detail of Galerius attacking Narseh on the Arch of Galerius at Thessaloniki, Greece, the city where Galerius carried out most of his administrative actions

Galerius had been reinforced, probably in the spring of 298, by a new contingent collected from the empire's Danubian holdings. Narseh did not advance from Armenia and Mesopotamia, leaving Galerius to lead the offensive in 298 with an attack on northern Mesopotamia via Armenia. Diocletian may or may not have been present to assist the campaign. Narseh retreated to Armenia to fight Galerius' force, to Narseh's disadvantage; the rugged Armenian terrain was favorable to Roman infantry, but unfavorable to Sassanid cavalry. In two successive battles, Galerius secured major victories over Narseh. During the second encounter, Roman forces seized Narseh's camp, his treasury, his harem, and his wife along with it. Galerius continued moving down the Tigris, taking the Persian capital at Ctesiphon before returning to Roman territory.

Peace negotiations

Narseh had previously sent an ambassador to Galerius to plead for the return of his wives and children, but Galerius had dismissed this ambassador, reminding him of how Shapur had treated Valerian. The Romans, in any case, treated Narseh's captured family with tact, perhaps seeking to evoke comparisons to Alexander and his beneficent conduct towards the family of Darius III. Peace negotiations began in the spring of 299, with both Diocletian and Galerius presiding. Their magister memoriae (secretary) Sicorius Probus was sent to Narseh to present terms.

The conditions of the peace were heavy: Persia would give up territory to Rome, making the Tigris the boundary between the two empires. Further terms specified that Armenia was returned to Roman domination, with the fort of Ziatha as its border; Caucasian Iberia would pay allegiance to Rome under a Roman appointee; Nisibis, now under Roman rule, would become the sole conduit for trade between Persia and Rome; and Rome would exercise control over the five satrapies between the Tigris and Armenia: Ingilene, Sophanene (Sophene), Arzanene (Aghdznik), Corduene, and Zabdicene (near modern Hakkâri, Turkey). These regions included the passage of the Tigris through the Anti-Taurus range; the Bitlis pass, the quickest southerly route into Persian Armenia; and access to the Tur Abdin plateau. With these territories, Rome would have an advance station north of Ctesiphon, and would be able to slow any future advance of Persian forces through the region. Under the terms of the peace Tiridates would regain both his throne and the entirety of his ancestral claim, and Rome would secure a wide zone of cultural influence in the region.

Religious persecutions

Main article: Diocletianic Persecution

See also: Persecution of early Christians in the Roman Empire

Early persecutions

At the conclusion of the peace, Diocletian and Galerius returned to Syrian Antioch. At some time in 299, the emperors were engaged in sacrifice and divination in an attempt to predict the future. The haruspices were unable to read the sacrificed animals, and blamed Christians in the imperial household for it. The emperors declared that all members of the court perform an act of sacrifice. Following this, the emperors sent letters to the military command, demanding the entire army to either perform the required sacrifices or else face discharge. Diocletian was conservative in matters of religion, a man faithful to the traditional Roman pantheon and understanding of demands for religious purification, but Eusebius, Lactantius and Constantine each state that it was Galerius, not Diocletian, who was the prime facilitator of the purge, and its prime beneficiary. Galerius, even more devoted and passionate than Diocletian, perhaps saw political advantage in persecutionary politics, and was willing to break with a government policy of inaction on the issue.

Affairs quieted after the initial persecution. Diocletian remained in Antioch for the following three years. He visited Egypt once, over the winter of 301–2, where he began the grain dole in Alexandria. Following some public disputes with Manicheans, Diocletian ordered that the leading followers of Mani be burnt alive along with their scriptures. In a March 31 302 rescript from Alexandria, he declared that low-status Manicheans were to be executed by the blade, and high-status Manicheans were to be sent to work in either the quarries of Proconnesus (Marmara Island, Turkey) or the mines of Phaeno in southern Palestine. All Manichean property was to be seized and deposited in the imperial treasury. Diocletian found much to be offended by in Manichean religion: its novelty, its alien origins, the way it corrupted the morals of the Roman race, and its inherent opposition to long-standing religious traditions. Manichaeanism was also supported by Persia at the time, compounding religious with international politics. The reasons for which he disliked Manichaenism were equally applicable, if not more so, to Christianity.

Catacomb of Saints Marcellinus and Peter on the Via Labicana. Christ between Peter and Paul. To the sides are the martyrs Gorgonius, Peter, Marcellinus, Tiburtius

Great Persecution

Diocletian returned to Antioch in the autumn of 302, where he ordered that the deacon Romanus of Caesarea have his tongue removed for defiling the order of the courts and interrupting official sacrifices. This being done, Romanus was sent to prison, where he would be executed on November 17 303. The arrogance of this Christian displeased Diocletian, and he left the city and made for Nicomedia for the winter, accompanied by Galerius. According to Lactantius, Diocletian and Galerius entered into an argument over what imperial policy towards Christians should be while wintering at Nicomedia in 302. Diocletian argued that forbidding Christians from the bureaucracy and military would be sufficient to appease the gods, while Galerius pushed for their extermination. The two men sought to resolve their dispute by sending a messenger to consult the oracle of Apollo at Didyma. Upon returning, the messenger told the court that "the just on earth" hindered Apollo's ability to speak. These "just", Diocletian was informed by members of the court, could only refer to the Christians of the empire. At the behest of his court, Diocletian finally acceded to demands for universal persecution.

On February 23 303, Diocletian ordered that the newly built church at Nicomedia be razed, its scriptures set to flame, and its precious stores collected as treasure. The next day, Diocletian's first "Edict against the Christians" was published. This ordered the destruction of Christian scriptures and places of worship across the Empire, and prohibited Christians from assembling for worship. Before the end of February, a fire destroyed part of the imperial palace. Galerius convinced Diocletian that the culprits were Christians, conspirators who had plotted with the eunuchs of the palace. An investigation was commissioned, but no responsible party was found. Executions followed. The palace eunuchs Dorotheus and Gorgonius were eliminated. One individual, a Peter, was stripped, raised high, and scourged. Salt and vinegar were poured in his wounds, and Peter was slowly boiled over an open flame. The executions continued until at least April 24 303, when six individuals, including the bishop Anthimus, were decapitated. A second fire occurred sixteen days after the first. Galerius left the city, declaring it unsafe. Diocletian would soon follow.

The persecutionary edicts would be ultimately unsuccessful: most Christians escaped punishment through silence or apostasy, returning to the faith in times of peace. Galerius would rescind the edict in 311, announcing that the persecution had failed to bring Christians back to traditional religion. Within twenty-five years of the persecution's inauguration, the Christian emperor Constantine would rule the empire alone. He would reverse the consequences of the edicts, and return all confiscated property to Christians. Under Constantine's rule, Christianity would become the empire's preferred religion.

Later life

Illness and abdication

File:SPLIT-Hebrard overall color restitution.jpg

Diocletian's Palace at Salona (Split, Croatia)

The journey from Nicomedia to Rome took most of the remainder of the year. Diocletian entered the city of Rome shortly before November 20 303. On that day, he celebrated, with Maximian, the twentieth anniversary of his reign (vicennalia), the tenth anniversary of the tetrarchy (decennalia), and a triumph for the war against the Persians. Diocletian soon grew impatient with the city. It did not give enough deference to his supreme authority; it expected him to act the part of the aristocratic ruler, not a monarchic one. On December 20 303, Diocletian left Rome without performing the ceremonies investing him with his ninth consulate. He would perform them on January 1 304 in Ravenna. There are suggestions in the Panegyrici Latini and Lactantius that Diocletian arranged plans for his and Maximian's future renunciation of power while in Rome. Maximian, according to these accounts, swore to uphold Diocletian's plan in a ceremony in the temple of Jupiter.

From Ravenna, Diocletian moved on to the Danube. There, potentially in Galerius' company, he took part in a campaign against the Carpi. He contracted a minor illness in the spring on the Danube before his arrival in Nicomedia on August 28. On November 20, he appeared in public to dedicate the opening of the circus beside his palace. Soon after the ceremonies, he collapsed. He became increasingly sick over the winter of 304–5; on December 13, he seemed to have finally died. The city was sent into a mourning from which it was only retrieved by rumors of his continuing life. Some skeptics alleged that Diocletian's death was merely being kept secret until Galerius could come to assume power. When Diocletian at last reappeared in public on March 1 305, he was emaciated and barely recognizable.

Later in March, Galerius arrived in the city. According to Lactantius, he came armed with plans to reconstitute the tetrarchy, force Diocletian to step down, and to fill the imperial office with men compliant to his will. Through coercion and threats, he eventually convinced Diocletian to comply with his plan. Lactantius also claims that he had done the same to Maximian at Sirmium previously. On May 1 305, Diocletian called an assembly of his generals, traditional companion troops, and representatives from distant legions. They met at the same hill, three miles out of Nicomedia, where Diocletian had been proclaimed emperor. In front of a statue of Jupiter, his patron deity, Diocletian addressed the crowd. With tears in his eyes, he told them of his weakness, his need for rest, and his will to resign. He declared that he needed to pass the duty of empire on to someone stronger.

Most in the crowd believed they knew what would follow: Constantine and Maxentius, the only adult sons of a reigning emperor, men who long been preparing to succeed their fathers, would be granted the title of Caesar. Constantine had traveled through Palestine at the right hand of Diocletian, and was present at the palace in Nicomedia in 303 and 305. It is likely that Maxentius received the same treatment. In Lactantius' account, when Diocletian announces that he was to resign, the entire crowd turned to face Constantine. It was not to be: Severus and Maximin were declared Caesars. Maximin appeared at the scene, taking his robes from Diocletian. On the same day, Severus would receive his robes from Maximian in Milan. Constantius succeeded Maximian as Augustus of the West, but Constantine and Maxentius, individuals who had been trained for the position, were entirely ignored in the transition of power. This did not bode well for the future security of the tetrarchic system.

Retirement and death

Diocletian retired to his homeland, to the expansive palace he had built in Dalmatia near the administrative center of Salona on the Adriatic. Maximian retired retired to villas in Campania and Lucania. The regions were distant from political life, but Diocletian and Maximian were close enough to remain in regular contact with each other. Galerius assumed the consular fasces in 308 with Diocletian as his colleague. In the autumn of 308, Galerius again conferred with Diocletian at Carnuntum (Petronell-Carnuntum, Austria). Diocletian and Maximian were both present on November 11 308, to see Galerius appoint Licinius to be Augustus in place of Severus, who had died at the hands of Maxentius. He ordered Maximian, who had attempted to return to power after his retirement, to step down permanently. At Carnuntum Galerius begged Diocletian to return to the throne, to resolve the conflicts that had arisen through Constantine's rise to power and Maxentius' usurpation. Diocletian's reply: "If you could show the cabbage that I planted with my own hands to your emperor, he definitely wouldn’t dare suggest that I replace the peace and happiness of this place with the storms of a never-satisfied greed."

He lived on for three more years, spending his days occupied in his gardens. He would have seen his tetrarchic system collapsing around him, torn by the selfish ambitions of his successors. He would have heard of Maximian's third claim to the throne, his forced suicide, his damnatio memoriae. In his own palace, statues and portraits of the two emperors together were torn down, destroyed. Deep in despair and illness, Diocletian perhaps even personally accelerated the advent of his death. He died on December 3 311.

Reforms

Tetrarchic and ideological

File:Diocletian's Palace.png

Modern view of Diocletian's Palace near Salona (in Split, Croatia)

Diocletian saw his work as that of a restorer, a figure of authority, whose duty it was to return the empire to peace, and recreate stability and justice where barbarian hordes had destroyed it. His reign saw the arrogation, regimentation and centralization of political authority on a massive scale: an imperial system of values was henceforth to be communicated to a provincial audience sometimes unwilling to listen. In the imperial propaganda from the period, recent history is perverted and minimized in the service of the theme. Aurelian's achievements are ignored, the revolt of Carausius is backdated to the reign of Gallienus, and it is implied that the tetrarchs engineered the defeat over the Palmyrenes. The period between Gallienus and Diocletian is effectively erased. The history of the empire before the tetrarchy is portrayed as a time of civil war, savage despotism, and imperial collapse. In those inscriptions that bear their names, Diocletian and his companions are referred to as "restorers of the whole world", men who succeeded in "defeating the nations of the barbarians, and confirming the tranquility of their world". Diocletian was written up as the "founder of eternal peace". The theme of restoration was conjoined to an emphasis on the uniqueness and accomplishments of the tetrarchs themselves.

The cities where emperors had lived so frequently in this period—Milan, Trier, Arles, Sirmium, Serdica, Thessaloniki, Nicomedia, and Antioch—eventually came to be treated as alternate imperial seats, to the exclusion of Rome and its senatorial elite. A new style of ceremony was developed, one which emphasized the distinction of the emperor from all other persons. The quasi-republican ideals of Augustus' primus inter pares were abandoned for all but the tetrarchs themselves. Diocletian took to wearing a gold crown and jewels, and forbade the use of purple cloth to all but emperors. His subjects would now need to prostrate themselves in his presence (adoratio); the most fortunate were allowed the privilege of kissing the hem of his robe (proskynesis, προσκύνησις). New circuses and basilicas were designed with the intention of keeping the face of the emperor always in view, always in a seat of authority. The emperor became a figure of transcendent authority, a man beyond the grip of the masses; his every appearance was stage-managed. This style of presentation was not new—many of its elements were first seen in the reigns of Aurelian and Severus—but it was only under the tetrarchs that it was refined and made into an explicit system.

Administrative

In keeping with his move from an ideology of republicanism to one of autocracy, Diocletian's council of advisers, his consilium, was dissimilar to those of earlier emperors. He eschewed the cosmetic appearances of the Augustan councils, which had been an often superficial attempt to demonstrate cooperation with the army and the Senate. In their place, an effectively autocratic structure came to dominate, signaling a shift later epitomized in the institution's name: it would become a consistorium ("consistory"), not a council. Diocletian began regulating his court by distinguishing separate departments (scrina) for different tasks. From this structure came the offices of different magistri, like the Magister officiorum ("Master of offices"), and associated secretariats. These were men suited to dealing with petitions, requests, correspondence, legal affairs, and foreign embassies. Within his court Diocletian maintained a permanent body of legal advisers, men who were to have significant influence on his re-ordering of juridical affairs. There were also two finance ministers, dealing with the separate bodies of the public treasury and the private domains of the emperor, and the praetorian prefect, the most significant person of the whole. Diocletian's reduction of the Praetorian Guards to the level of a simple city garrison for Rome lessened the civil powers of the office, but the office retained great power. The prefect kept a staff of hundreds and managed affairs in all segments of government: in taxation, administration, jurisprudence, and minor military commands, the praetorian prefect was often second only to the emperor himself.

To make for a more efficient collection of taxes and supplies, and to ease the enforcement of the law, Diocletian doubled the number of provinces from fifty to almost one hundred. The provinces were grouped into twelve dioceses, each governed by a new appointed official called a vicarius or vices agens praefectorum praetorio, or "deputy of the praetorian prefects". Some of the provincial divisions needed revision as well, and were modified either soon after 293 or early in the fourth century. The dissemination of imperial law to the provinces also increased under Diocletian's reign, for Diocletian's reform of the empire's provincial structures meant that there were now a greater number of governors ruling over smaller regions and smaller populations. Diocletian's reforms also shifted the governors' main function to that of the presiding official in the lower courts: whereas in the early empire military and judicial functions were the function of governor, and procurators had supervised taxation; under the new system vicarii and governors were responsible for justice and taxation, and a new class of duces ("dukes"), acting independently of the civil service, led military duties in the provinces. These dukes sometimes covered two or three of the new provinces created by Diocletian, and had forces ranging from two thousand to more than twenty thousand men.

Legal

A 1581 reprint of the Digestorum from Justinian's Corpus Juris Civilis (527–534). The Corpus drew on the codices of Gregorius and Hermogenianus, drafted and published under Diocletian's reign.

As with most emperors, much of Diocletian's daily routine rotated around legal affairs, responding to appeals and petitions, and delivering decisions. Rescripts, authoritative interpretations issued by the emperor in response to demands from disputants in both public and private cases, were a common duty of second- and third-century emperors. Diocletian was awash in paperwork, and was nearly incapable of delegating his duties. It would have been seen as a dereliction of duty to ignore them. Diocletian's praetorian prefects—Afranius Hannibalianus, Julius Asclepiodotus, and Flavius Constantius—aided in regulating the flow and presentation of such paperwork, but the deep legalism of Roman culture kept the workload heavy. Emperors in the forty years preceding Diocletian's reign did not manage these duties so effectively, and their output in attested rescripts fell precipitously. Diocletian, by contrast, was prodigious in his affairs: there are over 1,000 rescripts in his name still surviving, representing only a small portion of the total issued. His tirelessness in responding to rescripts serves as prelude to the more wide-ranging administrative and legal reforms that took place under his reign.

Under the governance of the jurists Gregorius, Aurelius Arcadius Charisius, and Hermogenianus, the imperial government began issuing official books of precedent, collecting and listing all the rescripts that had been issued from the reign of Hadrian (r. 117–138) to the reign of Diocletian. The Codex Gregorianus included rescripts up to 292, which the Codex Hermogenianus updated with a comprehensive collection of rescripts issued by Diocletian in 293 and 294. The jurists themselves were generally conservative, constantly looking to past Roman practice and theory for guidance. They were probably given a looser administrative structure than that imposed on the later compilers of the Codex Theodosianus (438) and Codex Justinianus (529). Their work, too, lacked the rigid structuring of those later codes, and was not published in the name of the emperor, but in the names of its compilers. But their policy of codification was radical in the decentralized institution that was the Roman law. There is a sharp increase in the number of edicts and rescripts produced under Diocletian's rule, a fact that has been read as evidence of the Diocletian's thoroughgoing effort to realign society on terms established by the imperial center.

After Diocletian's reform of the provinces, governors were often referred to by the name iudex, or judge. The governor became responsible for his decisions first to his immediate superiors, as well as to the more distant office of the emperor. It was most likely at this time that judicial records became verbatim accounts of what was said in trial, making it easier to determine bias or improper conduct on the part of the governor. With these records and the empire's universal right of appeal, central authorities probably had a great deal of power to enforce the proper behavior of their judges. In spite of Diocletian's attempts at reform, the provincial restructuring was far from clear, especially when citizens appealed the decisions of their governors. Proconsuls, for example, were often both courts of first instance and recipients of appeals, and the governors of some provinces took appellant cases from their neighbors. It soon became impossible to avoid taking some cases to the emperor for arbitration and judgment.

Military

It is archaeologically difficult to distinguish Diocletian's fortifications from those of his successors or predecessors. The Danubian earthworks known as the Devil's Dyke, for example, cannot even be securely dated to a particular century, but have still been attributed to Diocletian. The most that can be said about built structures under Diocletian's reign is that he rebuilt forts along the Rhine-Iller-Danube line, in Egypt, and on the frontier with Persia. Beyond that, much discussion is necessarily speculative, and reliant on the broad generalizations of written sources. Diocletian and the tetrarchs had no consistent plan for frontier advancement, and records of raids and forts built across the frontier are likely to indicate only temporary claims. The Strata Diocletiana along the eastern frontier is the classic Diocletianic frontier system, consisting of an outer road followed by tightly spaced forts followed by further fortifications in the rear.

Lactantius criticized Diocletian of causing excessive increase in troop sizes, declaring that "each of the four [Tetrarchs] strove to have a far larger number of troops than previous emperors had when they were governing the state alone." The fifth-century pagan Zosimus, by contrast, praised Diocletian for keeping troops on the borders, rather than keeping them in the cities, as Constantine was held to have done. Both these views had some truth to them, despite the biases of their authors: Diocletian and the tetrarchs did greatly expand the army, and the growth was predominantly in frontier regions, although it is difficult to establish the precise details of these shifts given the weakness of the sources. From levels of around 390,000 in 285 the army was expanded to a new total of 581,000. The growth was smaller in the East, which only expanded from 253,000 men to 311,000, most of whom manned the Persian frontier. The navy's forces increased from approximately 46,000 to approximately 64,000.

Diocletian's increases in the size of the civil service and the military forces of his empire meant that the empire's tax burden would also increase, especially given how the military was the largest burden on the imperial budget. The proportion of the adult male population serving in the army was increased from roughly 1 in 25 to 1 in 15, an increase judged excessive by some modern commentators. Official troop allowances were kept to low levels, and the mass of troops often resorted to extortion or the taking of civilian jobs. Arrears became the norm for most troops. Many were even given payment in kind in place of their salaries. Were he unable to pay for his enlarged army, there would likely be civil conflict, potentially open revolt. Diocletian was led to devise a new system of taxation.

Economic

Taxation

Diocletian introduced an extensive new tax system based on heads (capita) and land (iuga) and tied to a new census of the empire's population and wealth. Census officials traveled throughout the empire, assessed the value of labor and land for each landowner, and joined the landowners' totals together to make totals of capita and iuga for all land administered by a city. The iugum was not a consistent measure of land, but varied according to the type of land, the type of crop, and the amount of labor necessary for sustenance on the land. The caput was not consistent either: women, for instance, were often valued at half a caput, and sometimes at other values. Livestock were also included in the tax, as part of a capitatio animalium. The city was instructed to provide animals, money, and manpower in proportion to its capita, and grain in proportion to its iuga.

Most taxes were due on each September 1, and levied from individual landowners by decuriones (decurions). These decurions, analogous to city councilors, were also responsible for withdrawing from their own stocks what they failed to collect from the populace. Diocletian's reforms also increased the number of financial officials in the provinces: more rationales and magistri privatae are attested under Diocletian's reign than before. These offices were to manage imperial properties and to supervise the collection of revenue. Despite the instability of the coinage, most taxes were either levied in or convertible into money, with shifting rates to take inflation into account. In 296, Diocletian issued an edict reforming census procedures. This edict introduced a general five-year census for the whole empire, replacing the previously periodic censuses that had operated at different speeds throughout the empire, and The kept up with changes in the values of capita and iuga. In the interests of securing a generally egalitarian tax system, Italy, which had long been exempt from taxes, was exempt no longer. Save for the city of Rome and a region extending one hundred miles in every direction from the city center (the Suburbicarian dioceses), Italy would now be taxed on the same level as any other province.

Diocletian's edicts emphasize the common liability of all taxpayers. Public records of all taxes would be established to enhance the transparency of the operation, so that taxpayers would understand how much their neighbors paid. The position of decurion had long been an honor sought by wealthy aristocrats. While tax collection had always been part of the job description, under Diocletian, its requirements became much more rigorous, and its holders and the city as a whole could be bankrupted if production figures fell. The Roman populace, long accustomed to irregular and ineffective tax collection, went through an uncomfortable period of adjustment to Diocletian's reforms. But even the lower classes were able to pay this burden, and the benefits to the people were clear: the new taxes were predictable, regular, and fair, and with payment came freedom from fear. Citizens of the fourth century, safe behind the frontiers established and paid for by their taxes, no longer had to fear foreign occupation.

Currency and inflation

A fragment of the Edict on Maximum Prices (301), on display in Berlin

By the early 280s, market forces had created a stable exchange rate between gold and the copper antoninianus, more or less stablizing commodity prices. The antoninianus, which had become the standard medium of exchange, was valued at one sixty-thousandth the value of a pound of gold. But Aurelian's measures had not solved the problem entirely, and inflation remained a serious issue. In the wake of a brief period of re-inflation, Diocletian began a more comprehensive reform of the currency in 293. The new system consisted of five coins: the aureus/solidus, a gold coin weighing, like its predecessors, one-sixtieth of a pound; the argenteus, a coin weighing one ninety-sixth of a pound and containing ninety-five percent pure silver; the follis, sometimes referred to as the laureatus A, a copper coin with added silver struck at the rate of thirty-two to the pound; the radiatus, a small copper coin struck at the rate of 108 to the pound, with no added silver; and a coin known today as the laureatus B, a smaller copper coin struck at the rate of 192 to the pound. The denarius was dropped from the imperial mints, though the values of new coins continued to be measured in reference to it.

By 301, however, the system was in trouble, straining under a new bout of inflation. Diocletian therefore issued his Edict on Coinage, re-tariffing all debts so that the nummii, the most common coin in circulation, would be worth half as much. In the edict, preserved in an inscription from the city of Aphrodisias in Caria (near Geyre, Turkey), it was declared that all debts contracted before September 1 301 were to be repaid at the old standards, while all debts contracted after that date were to be repaid at the new standards. It appears that the edict was made in an attempt to preserve the current price of gold, for which the official rate was approximately twenty percent beneath the market rate, and to keep the empire's coinage on silver, the traditional choice for Roman currency.

The Edict on Maximum Prices (Edictum De Pretiis Rerum Venalium in Latin) was issued two to three months after the coinage edict, somewhere between November 20 and December 10 301. It survives in many different versions, written on wood, papyrus, and stone. It is the best-preserved Latin inscription surviving from the Greek East. In the edict, Diocletian declares that the current pricing crisis came as a result of the unchecked greed of merchants, and had resulted in turmoil for the mass of common citizens. The language of the edict calls on the people's memory of their benevolent leaders, and exhorts them to, in loyalty to their emperors, enforce the provisions of the edict, and restore perfection to the world. The edict goes on to list in detail over one thousand goods and accompanying retail prices, prices that were not to be exceeded. Penalties are laid out for various pricing transgressions.

In the most basic terms, the edict was ignorant of the law of supply and demand. It ignored the fact that prices might vary from region to region, that they might vary according to their availability, and it ignored the impact of transportation costs in the retail pricing of goods. In the judgment of the historian David Potter, the whole edict was "an act of economic lunacy." The edict's penalties were applied unevenly across the empire, widely resisted, and were eventually dropped, potentially within a year of the edict's first issuance. Lactantius has written of the perverse accompaniments to the edict; of goods withdrawn from the market, of brawls over minute variations in price, of the deaths that came when its provisions were enforced. His account may be true, but it seems to modern historians somewhat exaggerated and hyperbolic in the telling, and the impact of the law is recorded in no other ancient source.

Legacy

The historian A.H.M. Jones has observed that "It is perhaps Diocletian's greatest achievement that he reigned twenty-one years and then abdicated voluntarily, and spent the remaining years of his life in peaceful retirement". Diocletian was one of the few emperors of the third and fourth centuries to die naturally. Once he retired, however, his tetrarchic system collapsed upon itself. Without the guiding hand of Diocletian, the empire frequently broke into civil war. Only in 324, when Constantine alone emerged triumphant, would stability return. Under the Christian Constantine, all of Diocletian's achievements would be repudiated. But Constantine's rule would validate Diocletian's achievements and the autocratic principle he represented: the borders were secure, in spite of Constantine's large expenditure of forces during his civil wars; the bureaucratic transformation of Roman government would be completed; and the court ceremonies embraced by Diocletian would be made more extravagant under Constantine.

Constantine would abandon Diocletian's aim of preserving a stable silver coinage in favor of the new gold solidus. Diocletian's paganism would be repudiated in favor of an imperially sponsored Christianity; his attempts at controlling prices ignored. But even Christianity became tied to the state structure of the Roman Empire in an autocratic way; Constantine claimed for himself as close a relationship with the Christian God as Diocletian had claimed with Jupiter. Most importantly, Diocletian's tax system would be preserved, even tightened. Aided by the new state machinery introduced by Diocletian, the Byzantine Empire would last for over one thousand years after his death.

References

• Banchich, Thomas M. "Iulianus (ca. 286–293 A.D.)." De Imperatoribus Romanis (1997). Accessed March 8, 2008.
• Barnes, Timothy D. "Lactantius and Constantine." The Journal of Roman Studies 63 (1973): 29–46.
• Barnes, Timothy D. "Two Senators under Constantine." The Journal of Roman Studies 65 (1975): 40–49.
• Barnes, Timothy D. "Sossianus Hierocles and the Antecedents of the "Great Persecution"." The Journal of Roman Studies 80 (1976): 239–52.
• Barnes, Timothy D. Constantine and Eusebius. Cambridge, MA: Harvard University Press, 1981. ISBN 978-0674165311
• Barnes, Timothy D. The New Empire of Diocletian and Constantine. Cambridge, MA: Harvard University Press, 1982. ISBN 0783722214
• Bleckmann, Bruno. "Diocletianus." In Brill's New Pauly, Volume 4, edited by Hubert Cancik and Helmut Schneider, 429–38. Leiden: Brill, 2002. ISBN 9004122591
• Bowman, Alan K., Peter Garnsey, and Averil Cameron. The Cambridge Ancient History, Volume XII: The Crisis of Empire. Cambridge University Press, 2005. ISBN 0-521-30199-8
• Brown, Peter. The Rise of Western Christendom. Oxford: Blackwell Publishing, 2003. ISBN 0-631-22138-7
• Burgess, R.W. "The Date of the Persecution of Christians in the Army". Journal of Theological Studies 47:1 (1996): 157–158.
• Corcoran, "Before Constantine", Simon. "Before Constantine." In The Cambridge Companion to the Age of Constantine, edited by Noel Lenski, 35–58. New York: Cambridge University Press, 2006. Hardcover ISBN 0-521-81838-9 Paperback ISBN 0-521-52157-2
• DiMaio, Jr., Michael. "Constantius I Chlorus (305–306 A.D.)." De Imperatoribus Romanis (1996a). Accessed March 8, 2008.
• DiMaio, Jr., Michael. "Galerius (305–311 A.D.)." De Imperatoribus Romanis (1996b). Accessed March 8, 2008.
• DiMaio, Jr., Michael. "L. Domitius Domitianus and Aurelius Achilleus (ca.296/297–ca.297/298)." De Imperatoribus Romanis (1996c). Accessed March 8, 2008.
• DiMaio, Jr., Michael. "Maximianus Herculius (286–305 A.D)." De Imperatoribus Romanis (1997). Accessed March 8, 2008.
• Elliott, T. G. The Christianity of Constantine the Great. Scranton, PA: University of Scranton Press, 1996. ISBN 0-940866-59-5
• Harries, Jill. Law and Empire in Late Antiquity. Cambridge: Cambridge University Press, 1999. Hardcover ISBN 0-521-41087-8 Paperback ISBN 0-521-42273-6
• Helgeland, John. "Christians and the Roman Army A.D. 173-337." Church History 43:2 (1974): 149–163, 200.
• Jones, A.H.M. The Later Roman Empire, 284–602: A Social, Economic and Administrative Survey. Baltimore: Johns Hopkins University, 1986.
• Leadbetter, William. "Carus (282–283 A.D.)." De Imperatoribus Romanis (2001a). Accessed February 16, 2008.
• Leadbetter, William. "Numerianus (283–284 A.D.)." De Imperatoribus Romanis (2001b). Accessed February 16, 2008.
• Leadbetter, William. "Carinus (283–285 A.D.)." De Imperatoribus Romanis (2001c). Accessed February 16, 2008.
• Lewis, Naphtali, and Meyer Reinhold. Roman Civilization: Volume 2, The Roman Empire. New York: Columbia University Press, 1990. ISBN 0-231-07133-7
• Liebeschuetz, J. H. W. G. Continuity and Change in Roman Religion. Oxford: Oxford University Press, 1979. ISBN 0-19-814822-4.
• Mackay, Christopher S. "Lactantius and the Succession to Diocletian." Classical Philology 94:2 (1999): 198–209.
• Mathisen, Ralph W. "Diocletian (284–305 A.D.)." De Imperatoribus Romanis (1997). Accessed February 16, 2008.
• Odahl, Charles Matson. Constantine and the Christian Empire. New York: Routledge, 2004. Hardcover ISBN 0-415-17485-6 Paperback ISBN 0-415-38655-1
• Potter, David S. The Roman Empire at Bay: AD 180–395. New York: Routledge, 2005. Hardcover ISBN 0-415-10057-7 Paperback ISBN 0-415-10058-5
• Rees, Roger. Diocletian and the Tetrarchy. Edinburgh: Edinburgh University Press, 2004. ISBN 0-7486-1661-6
• Southern, Pat. The Roman Empire from Severus to Constantine. New York: Routledge, 2001. ISBN 0-415-23944-3
• Rostovtzeff, Michael. The Social and Economic History of the Roman Empire. Oxford: Oxford University Press, 1966. ISBN 978-0198142317
• Treadgold, Warren. A History of the Byzantine State and Society. Stanford: Stanford University Press, 1997. ISBN 0-8047-2630-2
• Williams, Stephen. Diocletian and the Roman Recovery. New York: Routledge, 1997. ISBN 0-415-91827-8

See also

• Dioclesian, Henry Purcell's 1690 tragicomic semi-opera, loosely based on the life of the historical Diocletian

External links

• Diocletian from the Catholic Encyclopedia.
• 12 Byzantine Rulers, by Lars Brownworth. 15 minute audio lecture on Diocletian.
• Ruins of the Palace of the Emperor Diocletian at Spalatro in Dalmatia By Robert Adam, 1764. Plates made available by the University of Wisconsin Digital Collections Center. (N.B. "Spalatro" was a less used alternative form of "Spalato", the Italian name for Croatian "Split").