Key to Umbria

Porphyry figures (ca. 300 AD) of the First Tetrarchs

Originally from Acre: moved to Constantinople

Now on the exterior of the Basilica di San Marco, Venice 

Creation of the Tetrarchy (293 AD)

C. E. V. Nixon (in Nixon and Rodgers, referenced below, at page 46) succinctly captured the defining characteristic of Diocletian’s long reign as Augustus:

  1. “what appeared [in 284-5 AD] to be just another  3rd century coup d'état eventually led to the establishment of a new system of government [based on] rule by four emperors unrelated by blood, which gave the Roman Empire 20 years of stable government”. 

The first step towards the Tetrarchy had been the appointment of Maximian as Augustus in 286 AD.  The second step was the appointment of two Caesars, Constantius and Galerius, in 293 AD.

The principals upon which the new imperial college was founded were encapsulated in statue groups such as the one illustrated at the top of the page:

  1. The complete coherence of view between the imperial colleagues was captured by the fact that their individual features could not be discerned.

  2. They were represented in pairs, one pair looking east and one pair looking west.

  3. Each Augustus embraced ‘his’ Caesar in perfect amity.

  4. Each man had his left hand on his sword, ready to protect the Empire from danger from any direction.

A similar impression of harmony and authority is conveyed by a gold medallion (ca. 293 AD, minted at Treviri, illustrated at ANS 1967.153.38) from the Arras hoard, which also depicted the Tetrarchs in pairs:

  1. on the obverse: DIOCLETIANVS AVG ET MAXIMIANVS C (i.e. Diocletian and Galerius, respectively Augustus and Caesar in the east); and

  2. on the reverse: MAXIMIANVS AVG ET CONSTANTIVS C (i.e. Maximian and Constantius, respectively Augustus and Caesar in the west).

Peter Kiernan (referenced below, at p 43) noted:

  1. “The fact that no identifying attributes were used [for any of the busts on the medallion] shows that [the imperial colleagues] were represented as legitimate equals in the Tetrarchic system.  The theme of the medallion is a generic representation of the concordia, harmony, and similarity of the Roman world’s new leaders”.

That is not to say that the college lacked a leader: the empire was run from Diocletian’s court  and he enjoyed the status of ‘pater familias’.   As Aurelius Victor noted, the other Tetrarchs:

  1. “... looked up to [Diocletian] as to a father, or as one would to a mighty god” (De Caesaribus39:29).

It says much for his charisma and for the respect that he inspired that he was able to make this complex administrative machinery work so well.

Appointment of the Caesars

It would be possible, on the basis of scant information recorded in sometimes unreliable early chronicles:

  1. to date the appointment of the new Caesars to any point between 1st April 292 AD and the 21st May 293 AD; and

  2. to question whether or not both of them were appointed on the same day. 

However, the matter is cleared up in Panegyric VIII (translated into English in Nixon and Rodgers, referenced below), which was delivered in ca. 297 AD at Constantius’ court, probably at Trier.  The panegyrist made two relevant remarks:

  1. -“... that divine birth of Your Majesties [i.e. the elevation of the Caesars, Constantius and Galerius], ... [was] a birth brighter than the very beginning of Spring, which gave it light ...” (2:2).

  2. -“O Kalends of March, as once you marked the beginning of the revolving years, so now you mark those of eternal Emperors” (3:11).

As the translator remarked (at note 8), despite the conflicting evidence of early chronicles, the second reference above:

  1. “... indicates unequivocally that the dies natalis of the Caesars Constantius and Galerius was celebrated [at the time of this speech] on 1st March, and one would naturally conclude that both Caesars were proclaimed on 1st March 293 AD”.

This is confirmed for Galerius by the fact that, having described his death in 311 AD, Lactantius noted:

  1. “His vicennial anniversary [i.e. the start of his 20th year in power] was to have been celebrated on the ensuing kalends of March [i.e. on 1st March 312 AD]” (‘De Mortibus Persecutorum’, 35:4)

The ceremonies at which the Caesars were appointed were thus carefully synchronised:

  1. Diocletian invested Galerius with the purple at his then place of residence, Sirmium (now Sremska Mitrovica in Serbia, some 55 km west of Belgrade); while

  2. Maximian similarly invested Constantius, probably at his new residence in Milan.

Lactantius’ account of the appointment of Galerius’ successor as Caesar in 305 AD (‘De Mortibus Persecutorum’, 19) suggests that appointments of this kind were public occasions that involved imposing ceremonial, designed to impress what was probably a predominantly military audience that the new Caesars derived their legitimacy directly from the Jovian and Herculean Emperors.

It was noted on the previous page, Maximian had not been given victory titles during the months he spent as Caesar, and neither had he enjoyed tribunician power.  The situation was completely different for the new Caesars:

  1. Timothy Barnes (referenced below, 1982, in Table 5, p 255) deduced that all four members of the imperial college shared in the victory titles awarded from 293 BC; and

  2. R. E. Smith (referenced below, at p 1061) demonstrated that the new Caesars enjoyed tribunician power from the outset.

Smith also demonstrated (at p 1062) that Diocletian took steps to improve the position of Maximian in the light of these new arrangements:

  1. From this point, Maximian shared the imperial anniversary of Diocletian, so that both men went on to celebrate their decennalia and vicennalia of the dates determined by Diocletian’ acclamation on 20th November 284 AD (i.e. these joint anniversaries were celebrated on that day in 293 AD and 303 AD respectively). 

  2. Maximian’s years of tribunician power were increased to make up for the fact that he had not enjoyed this status as Caesar.  Thus, in an inscription (CIL XIII 5249) on the foundation stone form the fort at Vitudurum, which dates to ca. 293 AD, Diocletian has trib(unicia) pot(estate) XI and Maximian trib(unicia) pot(estate) X.

The Caesars’ Qualifications

Diocletian’s reasons for selecting Constantius and Galerius for these new appointments are not explicitly stated in the surviving sources.  As set out ion the previous page, it seems that Constantius had served Maximian in a senior capacity for some years prior to 293 AD.  The same was presumably true of the relationship between Diocletian and Galerius.  Aurelius Victor noted that:

  1. “All these men [i.e. Diocletian. Maximian, Constantius and Galerius] were natives of Illyria [probably best translated in this context as the extensive area that we now call the Balkans].  Although they were comparatively uncultured, they were of the greatest value to the State, being brought up to all the hardships of rural life and war ... Their native abilities and military skills, which they had acquired under the command of [the Emperors] Aurelian and Probus, almost made up for their lack of noble character, as is proved by the harmony that prevailed between them” (De Caesaribus39:26-9).

(This translation is taken from Stephen Williams (referenced below, at p. 69)

Dynastic Marriages

According to the ‘Origo Constantini Imperatoris’: 

  1. “With Galerius, [Constantius] was appointed Caesar by Diocletian: for he [Constantius] put away his former wife Helena and married Theodora, daughter of Maximianus, by whom he afterwards had six children, brothers of [Constantius’ son from his first marriage, the future Emperor] Constantine.” (1:2).

A similar account of these events was given by Aurelius Victor (although he has Theodora as Maximian’s stepdaughter):

  1. “.... [Diocletian and Maximian] appointed as Caesars and made marriage alliances with Julius [sic ?] Constantius and Galerius Maximianus ... After annulling their previous marriages: the former received the stepdaughter of Herculius [Maximian]; the latter Diocletian's daughter ...” (De Caesaribus39:18-9).

These and similar accounts imply that Constantius divorced Helen and married Theodora at the time of his elevation.  However, is clear from the discussion on the previous page that this marriage had probably taken place some five years earlier.  There is no comparable evidence for the dating of Galerius’ marriage to Diocletian’s daughter, Valeria, but it might well have similarly pre-dated his elevation.

Nomenclature, Seniority and Succession

Constantius’ original name seems to have been Flavius Constantius.  According to Lactantius, Galerius had originally been called Galerius Maximinus, but: 

  1. “Diocletian  .. bestowed on [him] the name of Maximian [i.e. changed Maximinus to Maximianus], ... because Maximian Herculius had served [Diocletian] with unshaken fidelity” (‘De Mortibus Persecutorum’, 18:13).

In addition, each new Caesar adopted elements of the official name of ‘his’ Augustus.  Thus, Timothy Barnes (referenced below, 1982, at p 4) established the Tetrarchs’ official names in the period 293-305 AD as:

  1. Gaius Aurelius Valerius Diocletianus (Diocletian); and

  2. his Caesar, Gaius Galerius Valerius Maximianus.

  3. Marcus Aurelius Valerius Maximianus (Maximian); and

  4. his Caesar, Marcus Flavius Valerius Constantius.

Each Caesar also received the signum of ‘his’ Augustus.  Thus:

  1. Galerius is sometimes given the signum Iovius in inscriptions (see, for example, CIL 03 5325); and 

  2. Constantius is described in a panegyric (Panegyric IX, translated into English in Nixon and Rodgers, referenced below) in the late 290s AD as “Caesar Herculius”, who derived inspiration from:

  3. “... both his grandfather, Hercules, and his father, Herculius [i..e Maximian]” (8:1).

Although he was assigned to Maximian rather than Diocletian, Constantius was the senior of the two new Caesars.  Thus he preceded Galerius in all three of the documents cited by Timothy Barnes (referenced below, 1982, at p 17-20) to establish the precise imperial titulature of the period.  Since both men had been appointed at the same time, we must presume that Constantius was older and more experienced than his new colleague.  As Bill Leadbetter (referenced below, at p 64) observed:

  1. “[Constantius] may have been as much as fifteen years older than Galerius and his attested career included a provincial governorship.  Nothing of the sort is known for Galerius.  An older man with a more distinguished record naturally outranked the promising newcomer in an army where seniority had always counted”.

It is sometimes asserted that each of the Augusti formally adopted ‘his’ Caesar as his son.  Whether or not this was the case, the title Caesar would have been construed as Emperor-designate (as it had since at least the time of the Emperor Vespasian). 

  1. Since Diocletian had no son of his own, his son-in-law Galerius was, in any case, his natural successor. 

  2. However, there were more fundamental consequences in the case of Maximian: his immediate successor would now be his son-in-law Constantius rather than his son, Maxentius (who was probably about ten years old at this time).

Diocletian’s Motivation

Unfortunately, while the putative reasons for which Diocletian created the Tetrarchy are given in the early sources, many of the details in these accounts does not stand up to scrutiny.  For example, Aurelius Victor was probably correct when he placed the creation of the Tetrarchy in the context of Carausius’ usurpation of Britain (described on the previous page).  However, he added other contributory factors:

  1. “At the same time ...

  2. -the Persians were causing serious disturbances in the east;

  3. -Julianus and the Quinquegentianian peoples [were doing likewise] in Africa; [and]

  4. - ... at Alexandria in Egypt, someone named Achilleus had donned the insignia of supreme power.

  5. For these reasons, [Diocletian and Maximian] appointed as Caesars ...” (De Caesaribus39:18-9)

In fact, these all seem to be later problems that faces the Tetrarchs (as we shall see in more detail below):

  1. Until King Narses declared war on Rome in 296 AD, the situation in relation to Persia was unsettled but not acutely dangerous.

  2. The problem in lower Egypt only erupted with the revolt of Lucius Domitius Domitianus, which probably occurred in 297 AD.  Aurelius Achilleus is probably identified here as the leader of the revolt because, after the death of Domitianus, he commanded the rebels during the siege of Alexandria, which lasted until at least March 298 AD (Timothy Barnes, referenced below, 1982, at pp 11-2).

  3. Maximian suppressed the incursions into the African provinces by the Quinquegentiani (five Berber tribes) in 297-9 AD (Timothy Barnes, referenced below, 1982, at p 58).

The immediate pressures in 293 AD that led to the appointments of the Caesars (other than the revolt of Carausius) are therefore best determined from their subsequent assignments (as deduced by Timothy Barnes, referenced below, 1982, at pp 60-2):

  1. Constantius, who took over Maximian’s palace at Trier, expelled Carausius from north west Gaul soon after his appointment.  He then devoted the next three years to the difficult challenge of mounting a naval invasion of Britain.   Maximian was thus free to established his main residence at Milan from which he could attend to the affairs of the rest of the western part of the Empire.

  2. Galerius probably established a residence at Antioch as a base from which he suppressed a revolt in upper Egypt (which was quite distinct from the later rebellion of  Domitius Domitianus).  This left Diocletian free to continue his campaign against Sarmatian incursions into the Hungarian plains from his base at Sirmium.

While immediate pressures, and particularly the need to regain Britain for the Empire, probably influenced the timing of the decision, Diocletian’s new experiment was part of a longer-term view of how the Empire could best be managed.  In my view, the superficial symmetry of his new imperial college obscures the different ways in which it operated (and was designed to operate) in the west and in the east.

  1. Constantius was an experienced administrator and strategist to whom Maximian was able to delegate all aspects of the administration of Gaul and (after its recovery) of Britain.  He was completely credible as a continuing imperial presence there, and never betrayed any aspiration to be anything else (at least as we can tell from surviving sources).  Maximian was by no means excluded from the affairs of Gaul, but neither did they demand a great deal of his attention (except during the height of Constantius’ invasion of Britain).

  2. Galerius was a younger and probably a more energetic man than Constantius, and was first and foremost a brave and sometimes impetuous military commander.  He became Diocletian’s right-hand man in the military sphere, where he could make up for some of Diocletian’s own deficiencies.  Diocletian himself still engaged in military operations.  However, once he could rely on Galerius to deal with military emergencies as they arose.  In particular, he could (and did) delegate many of the demands from the east to Galerius while he continued with the vital consolidation of the frontier on the Danube.

Praetorian Prefects

While Maximian and, after 293 AD the two Caesars, assisted Diocletian primarily with military matters, his most important support in the civic sphere came from the Praetorian Prefects, who were responsible for the administration of justice and tax collection across the Empire.  The epigraphic analysis of Pierfranceso Porena (referenced below) has demonstrated that Diocletian used a college of two Praetorian Prefects throughout his reign, one attached to each Augustus, and that the arrangements were separate from and undisturbed by the appointment of the Caesars.  Scholars used to believe that Constantius (certainly) and Galerius (probably) had held the post of Praetorian Prefect prior to their incorporation into the imperial college.  However, the analysis mentioned above renders it unlikely that either of them ever held one of these posts. 

As described on the previous page, the two Praetorian Prefects serving in 293 AD were:

  1. Afranius Hannibalianus, whom Diocletian had probably appointed at the time of his acclamation; and

  2. Julius Asclepiodotus, who had probably replaced Aurelius Aristobulus at the time of Maximian’s elevation to the rank of Augustus, and who seems to have been assigned to him from that point. 

Both men had been designated as the Consuls of 292 AD, possibly to secure their continued loyalty in the changed environment thereafter.

The Praetorian Prefects had a representative in Rome, presumably since neither of them was based there.  The earliest evidence for this is an inscription (CIL VI 1125; LSA-820) on the base of a statue of Maximian that was found in 1530, in what were then the Farnese Gardens on the north slope of the Palatine:

Magno et Invicto ac/ super omnes retro/ principes, fortissimo

Imp(eratori) Caes(ari) M(arco) Aur(elio) Valerio/ Maximiano

Pio, Fel(ici)/ Invicto Aug(usto), co(n)s(uli) IIII/ p(atri) p(atriae), proco(n)s(uli)

Septimius Valentio, v(ir) p(erfectissimus)

a(gens) v(icem) praeff(ectorum) praett(orio) cc(larissimorum) vv(irorum)

d(evotus) n(umini) m(aiestati)q(ue) eius.

To the great and invincible and (above all previous emperors) most powerful

Emperor Caesar Marcus Aurelius Valerius Maximianus

pious, fortunate, invincible Augustus, consul for the fourth time

father of the country, proconsul

Septimius Valentio, of perfectissimus rank

vicar of the two Praetorian Prefects of clarissimus rank,

(set this up), devoted to his divine spirit and majesty

Since Maximian had held the Consulship four times when this base was inscribed, it can be dated to the period 293-6 AD (i.e. to the period from the start of his fourth until that of his fifth year as Consul).  Since Septimius Valentio was the vicar of two Praetorian Prefects of clarissimus rank, we can reasonably assume that these were still Afranius Hannibalianus and Julius Asclepiodotus, who (as noted on the previous page) had attained this rank in 292 AD.  While Praetorian Prefects had sometimes had vicars in Rome in the past, the practice seems to have become permanent only at this point, and perhaps acted as a precursor to the wider administrative reforms that were soon to be put in place across the Empire.  (It is tempting to speculate that this was one of four statues of the Tetrarchs, which Septimius Valentio erected to mark the formation of the Tetrarchy in 293 AD.)

An inscription (AE 1987, 456; LSA 1603) that was discovered in 1983 on the base of a statue of the Caesar Constantius during excavations near Brescia in Lombardy (published by André Chastagnol, referenced below) indicates a subsequent change in the membership of the college of Praetorian Prefects:

[F]lavio V[alerio]| Constan[tio], fortissim[o ac]| nobiliss(imo) Ca[es(ari)

[I]ulius Asclepio[dotus]| v(ir) c(larissimus) et

Aur(elius) Her[mo|g]enianus v(ir) [em(inentissimus)]|

praeff(ecti) prae[t(orio)]| d(evoti) n(umini) m(aiestati)q(ue) eius

To Flavius Valerius Constantius, most powerful and noble Caesar

Julius Asclepiodotus, of Senatorial rank and

Aurelius Hermogenianus, of equestrian rank,

Praetorian Prefects

devoted to [Constantius’] divine spirit and majesty, [set this up]

Thus, while Julius Asclepiodotus  was still in place, his colleague Afranius Hannibalianus (above) had been replaced by Aurelius Hermogenianus.  We can estimate the date at which this had occurred by considering what is known from other sources about their respective careers:

  1. Julius Asclepiodotus was still Praetorian Prefect in the west in 296 AD, when the Chronicle of St Jerome recorded:

  2. “After ten years, Britain [was] recovered by Asclepiodotus, the Praetorian Prefect”.

  3. Aurelius Hermogenianus, who was an accomplished jurist, seems of have been at work on the Codex Hermogenianus (Hermogenian Code) for Diocletian in 293-4 AD.  Simon Corcoran (referenced below, 1996, at p 87) suggested that he probably worked in a similar capacity at Maximian’s court thereafter, preparing for a second edition of his work.  He presumably replaced Afranius Hannibalianus in January 297 AD, when Afranius Hannibalianus became Urban Prefect in Rome.

Pierfrancesco Porena (referenced below, at p 148-9) suggested that Julius Asclepiodotus and Aurelius Hermogenianus had commissioned this statue of Constantius during the year of his quinquennalia (which began on 1st March 297 AD), and that it had probably been accompanied by another of Galerius.  (A statue of Galerius in northern Italy would have been unlikely to have survived the political upheaval of the following decade, as we shall see). 

An inscription (CIL XIV 4455; LSA-1661) on the base of a statue from Ostia provides evidence for a second vicar of the Praetorian Prefects at Rome:

Manilio Rus[ticiano]/ v(iro) p(erfectissimo) praef(ecto) ann(onae)

a(genti) v(ices) pra[eff(ectorum) praetorio] emm(inentissimorum) vv(irorum)

curato[ri et p]atrono/ splendidissim(a)e col(oniae) Os[t(iensium)]

Ob eius fidem ac/merii  erga rem publicam

ordo/ et populus Ostiensium

[pro quo] civitas/ titulis administra[ti]onis eius/ fieret inlustr[ior], decrevit adq(ue)/ const[itui]t

To Manilius Rusticianus, of perfectissimus rank, prefect of the annona,

vicar of the Praetorian Prefects of most eminent rank

curator and patron of the most splendid colony of Ostia

On account of his trust and services towards the community

the council and people of Ostia, who by  his administration were made more noble

decreed and set [this statue] up

Manilius Rusticianus is also known to have been the Praetorian Prefect during the reign of Maxentius, probably in 311 AD.  Pierfrancesco Porena (referenced below, at p 145) suggested that this statue was dedicated to him in an earlier period in which he had represented the Tetrarchic Praetorian Prefects in Rome.  Since neither Praetorian Prefect had senatorial rank by this time, Julius Asclepiodotus must have been replaced by a man of equestrian rank.  Pierfrancesco Porena (referenced below, at p 145) cited documentary evidence for a vicar (Aemilius Rusticianus) of two equestrian Praetorian Prefects in Egypt in 298 AD, which confirms the hypothesis that Julius Asclepiodotus had left office shortly after his erstwhile Consular colleague, Afranius Hannibalianus.  Manilius Rusticianus therefore presumably acted as their vicar in Rome at some point after ca. 298 AD but before the coup of Maxentius in 306 AD.

Military Campaigns (293- 303 AD)

As noted below, in the preamble to his Edict on Maximum Prices of November 301 AD Diocletian claimed to have:

  1. “....stemmed the tide of the ravages of barbarian nations by destroying them ...” 

This had been Diocletian’s single most important aim when he created the the Tetrarchy, and it had been achieved through a string of victories.   Timothy Barnes (referenced below, 1982, Table 5, p 255) listed the victory titles that the Tetrarchs shared in the period 293-305 AD:

  1. Germanicus maximus (293 AD);

  2. Sarmaticus maximus (294 AD);

  3. Persicus maximus ( ?? ca. 295 AD);

  4. Britannicus maximus (296 AD);

  5. Carpicus maximus (296 AD);

  6. Persicus maximus (298 AD), with further titles for associated victories that were secured at this time in Armenia, Media, and Adiabene;

  7. Sarmaticus maximus (ca. 300 AD); and

  8. Germanicus maximus (ca. 300 AD).

The campaigns that led to these victories (and others that were not commemorated in official imperial titles) are discussed in two following pages:

  1. Maximian and Constantius in the West; and

  2. Diocletian and Galerius in the East.

In summary, while the borders along the Rhine and the Danube continued to demand imperial attention (despite the victories claimed agains the ‘Germans’ on the Rhine and the Carpi and Sarmatians on the Danube), Diocletian’s claims for having secured the peace of the Empire were clearly justified.  The most important achievements in this context were:

  1. the recovery of Britain for the Empire in 296 AD, which put an end to what had been a tempting example for other would-be usurpers; and

  2. the defeat of the Persian King Narses and the subsequent peace treaty in 299 AD, which avenged the humiliation that Romans had suffered some 40 years earlier and secured the eastern frontier for some 40 years to come.  

The most overt expression of Diocletian’s sense of having restored the security of the Empire came in 303 AD, when he made his first official entry into Rome to celebrate his vicennnalia (the 20th anniversary of his accession).   The occasion was recorded by Lactantius:

  1. “[Diocletian] set out ... for Rome [in 303 AD], there to celebrate the commencement of the 20th year of his reign.  That solemnity was performed on the 12th of the kalends of December [20th November]” (‘De Mortibus Persecutorum’, 17:1).

The sources make it clear that Diocletian used this occasion to celebrate a formal triumph for the many victories that the imperial colleagues had achieved in the previous decade.

  1. According to Eutropius, before their abdication (below) and thus surely on this occasion:

  2. “... [Diocletian and Maximian celebrated] a magnificent triumph ... at Rome over several nations, with a noble procession ... in which [pictures of the captured and subsequently released] wives, sisters,and children of Narseus were led before [the Emperors’] chariots” (‘Breviarium historiae Romanae’, 27:4).

  3. According the so-called Chronogaph of 354 AD:

  4. “ [Diocletian and Maximian] scattered gold and silver coins in the circus.  [Presumably on this occasion], the wall that formed the base of the seating for the boxes in the circus collapsed and crushed 13,000 people; and a woman named Irene gave birth to three boys and a girl.  [The Emperors] placed [representations of] the king of the Persians with [similar representations of the leaders of other defeated] nations and their tunics of pearl, in number 32, around the temples.  They brought 13 elephants, 6 drivers and 250 horsemen into the city”.

(These two sources suggest that important royal prisoners (including, in the second case, Narses himself) had been exhibited in the flesh during this triumph, but I have amended this in square brackets, following the deductions of C. E. V. Nixon (referenced below, 1981, at p 75).  These events are discussed again in the  page on Diocletian, Maximian and Rome).

Administrative Reform

In the preamble to his Edict on Maximum Prices of November 301 AD (below), Diocletian stated:

  1. “As we recall the wars which we have successfully fought, we must be grateful ... for a tranquil world that reclines in the embrace of the most profound calm, and for the blessings of a peace that was won with great effort. ... Therefore we, who ... previously stemmed the tide of the ravages of barbarian nations by destroying them, must surround the peace which we [have] established for eternity with the necessary defences of justice”.

Although this sentiment was expressed to justify a particular piece of legislation, it applied more generally to Diocletian’s aspirations for the administration of the Empire throughout the Tetrarchic period: having instituted a system of government that could secure the borders of the Empire without creating problems of internal security, he now needed to take measures that would capture and make manifest the benefits of peace. 

Not all these reforms were successful, and even those that were were by no means universally popular.  Nevertheless, Diocletian now had a luxury that had been denied to his predecessors for more than a century: time and space in which he could concentrate on the administrative framework of the Empire.

Reform of the Provinces

Lactantius complained that:

  1. “... provinces were divided into minute portions [in frusta concisae, which Simon Corcoran (referenced below, 2009, at p 240) translated as ‘sliced and diced’], and many [provincial governors] and a multitude of inferior officers lay heavy on each territory, and almost on each city.  There were also many stewards of different degrees, and deputies of [governors]” (‘De Mortibus Persecutorum’, 7:4).

He was referring to Diocletian’s policy of dividing many of the imperial provinces into smaller units, with their governors hierarchically ranked:

  1. The Proconsuls of Africa Proconsularis and Asia, were men of senatorial rank who reported directly to the imperial authorities. 

  2. The other provinces were grouped into (originally twelve) dioceses (illustrated in this excellent map from Ian Mladjov's Resources), and their respective provincial governors (entitled Correctores or Consulares in other important provinces and Praesides (guardians) elsewhere) reported to Rome via a diocesan official entitled “Vicarius”.  The Vicari and Praesides were almost always equestrians (except in Italia - see below).

There has been much debate as to the motivation for these changes, with the consensus being the need for an improved method of administering justice and (probably most importantly) of assessing and collecting tax (see below).   Thus, provincial officials were almost all civilians, while the administrative structure of the army often transcended imperial boundaries.

Before Diocletian’s reforms, the cities of Italy had enjoyed a large measure of autonomy.   However, this situation became increasingly unsustainable as the administrative centre of the Empire moved away from Rome.  Following these reforms, most of peninsular Italy was assigned to one of 16 new provinces that were grouped in the new diocese of Italia, with each province governed by a corrector of senatorial rank.  However, Rome and its environs, including (importantly) its port at Ostia, remained outside the provincial structure: they continued to be administered by the praefectus urbi (Urban Prefect), who held the most powerful senatorial post and reported directly to the imperial authorities. 

Timothy Barnes (referenced below, 1982, p 225) reviewed the basis upon which earlier historians had dated these reforms to 297-8 AD, pointing out chronological errors in the underlying analysis.  He concluded:

  1. “It is more probable that Diocletian ordained the division of provinces and the creation of dioceses in 293 AD at a single stroke, that his reforms were put into effect immediately ... and that only minor changes were made thereafter”. 

It is thus possible that Septimius Valentio, the vicar of the two Praetorian Prefects in Rome in ca. 293 AD, was the first man to hold what might have been a permanent office that was on a par with that of the vicars of the dioceses.  If so, it is unclear how this function related to that of the Urban Prefect.

Reform of the Army

According to Lactantius:

  1. “ ... Diocletian, ... partly by avarice and partly by timid counsels, overturned the Roman empire.  For, ... the Empire having been quartered [following the creation of the Tetrarchy], armies were multiplied, and each of the four princes strove to maintain a [much larger] military force than any sole emperor had done in times past” (‘De Mortibus Persecutorum’, 7:2). 

Zosimus, however, the merits in Diocletian’s military policy:

  1. “... the Roman Empire ... by the care of Diocletian, was protected on its remote frontiers by towns and fortresses in which soldiers were placed.  It was impossible for the barbarians to pass them, because there was always a sufficient force to oppose their incursions” (‘Historia Nova’, 2:34:1).

Scholars are generally agreed that the army did expand under Diocletian.  However, estimates of the net size of the expansion are quite varied: while epigraphical evidence illuminates the increase in the number of legions and other military units, it is much more difficult to establish the extent to which the number of men in each unit reduced (as it almost certainly did).  There might have been an increase in the use the mobile units attached to the Augusti and the Caesares under Diocletian (as there certainly was under Constantine) but, if so, this does not seem to have been at the expense of the permanent border units.  Epigraphical evidence certainly points to an extensive programme of enhancement of the physical assets that supported the frontier army, notably along the Danube and the Euphrates. 

Amongst all this uncertainty, what is clear is that better border security meant higher costs, and thus higher taxation. 

Reform of Taxation

Lactantius was in no doubt about the link between a larger army and a larger civil administration on the one hand and higher taxes on the other:

  1. “There began to be fewer men who paid taxes than there were who received wages; so that the means of the farmers being exhausted by enormous impositions, the farms were abandoned, cultivated grounds became woodland, and universal dismay prevailed” (‘De Mortibus Persecutorum’, 7:3). 

What he failed to note was that the existing system of taxation had been incoherent and unpredictable, with the burden of taxation falling randomly and often on those least able to pay. 

Most historians credit Diocletian with the introduction of  a five-yearly census across the Empire so that taxpayers’ ability to pay could be established on a more systematic (and, potentially more equitable) basis.  Since the census applied to all the new dioceses, it covered the the previously exempt area of peninsular Italy that now belonged to the diocese of Italia, but it still excluded Rome and its environs (the location of many senatorial estates).   The reforms also included a system of budgeting that established the total amount of tax that needed to be raised (primarily for expenditure on the military), which were published as five-yearly indictions.  This total as allocated among the provinces, and local officials were made financially responsible for its collection.  The system allowed for taxes to be collected in kind, thereby securing some insulation from the growing problem with the imperial coinage.

In fact, the earliest evidence of this massive reform is contained in an Egyptian papyrus (P.Cair. Isid. 1) that recorded an edict issued on 16th March 297 AD by Aristius Optatus, the prefect of Egypt.  Its purpose had been to publicise and give effect in Egypt to another edict (now lost) that had been issued for the whole Empire by Diocletian (in the name of the Tetrarchs).  Since later censuses in 306 AD and 311 AD are securely documented, we can reasonably assume that Diocletian had instituted (or perhaps revitalised) the practice of taking five-yearly censuses in 296 AD.

Currency Reform and Monetary Policy 

The coins minted in the Empire had become debased during the 3rd century, to the point that they no longer represented a reliable store of wealth.  The Emperor Aurelian reformed the currency and improved its quality in 274 AD, but with no long-term effect.  Diocletian therefore undertook further reform in ca. 293 AD, when new high quality silver coins were minted for the first time in many years.  Erim and colleagues (referenced below) deuced that, from this point, the reformed coinage comprised:

  1. the aureus, a gold coin also known as the solidus that Diocletian had already improved earlier in the reign;

  2. the argenteus (mentioned above), so-named because it was almost pure silver, with a nominal value of 50 denarii;

  3. a new coin (now known as the follis, possibly originally known as the nummus), which was made of silver-washed copper and which had a nominal value of 10 denarii; and

  4. three smaller bronze coins: the denarius; the two denari piece; and the five denari piece.

This reformed coinage was produced at some fourteen mints (listed by Michael Hendy, referenced below), double the number that had existed at the start of Diocletian’s reign.  These were located at strategic locations across the Empire (mostly chosen to meet the needs of the army), and most of the new dioceses (above) had at least one.

The value of the metal in the silver coins exceeded their nominal values, so they were minted at a loss, at least until the State began to requisition silver from the public at artificially low prices.  These coins were probably not minted in large quantities and, when those that were minted were probably hoarded rather than used in transactions.  In contrast, the smaller bronze coins were significantly over-valued, a factor that must have contributed significantly to the problem of price inflation.  Diocletian responded by issuing two edicts: 

  1. The Edict on Coinage (September 301 AD) is known from a single fragmentary inscription from Aphrodisias in  modern Turkey, which was published by Erim et al., referenced below.  Erim and his colleagues deduced that it decreed a doubling of the purchasing power of the argenteus and the follis, to 100 and 20 denarii respectively.

  2. The more famous Edict of Maximum Prices(November, 301 AD) is known from a large number of surviving  inscriptions, none of which is complete.  (They include large fragments now embedded in the church of St John Chrysostomos at modern Geraki in Greece, which Simon Corcoran describes in this video).   Roger Rees (referenced below) published a reconstruction of the Edict in English at pp 139-46.  It attempted to limit by law the prices of a wide variety of goods and of the associated transport and labour costs.   

The fragments of the inscription of the Edict on Coinage at Aphrodisias were found near others from an inscription of the Edict on Maximum Prices.  This is unsurprising since the two edicts were clearly two parts of a single excursion into what modern economists call a ‘command economy’.  (We might reasonably assume that they were routinely displayed together, and that the relative scarcity of inscriptions relating to the former is simply an accident of history).  Lactantius did not mention former but was duly (and justifiably) scathing about the latter:

  1. “... when by various extortions [Diocletian] had made all things exceedingly expensive, [he] attempted by an edict to limit their prices.  Then much blood was shed for the merest trifles; men were afraid to offer anything for sale, and the scarcity became ever more excessive until, in the end, the ordinance, ... from mere necessity, was abrogated” (‘De Mortibus Persecutorum’, 7:7-8). 

We can surely believe Lactantius when he claimed that the the policy failed in its objectives when market forces prevailed, and that it was then quietly abandoned.  Its most valuable contribution lies in the information that the associated inscriptions preserved for history on the dire state of the economy of Empire at this time and on the way that the causes of the problems were then perceived.  

Religious Persecution 

After some earlier setbacks, Christianity had been untroubled by official interference since 260 AD, when the Emperor Gallienuus had proclaimed religious toleration across the Empire.  However, this began to change after the Tetrarchs’ victory against the Persians.   An overview by Eusebius, who was then the Bishop of Caesarea in Palestine, gives a clear sense of the unexpectedness of this development: 

  1. “What words could sufficiently describe the greatness and abundance of the prosperity of the Roman government before the war against us [i.e. the Christians], while the rulers were friendly and peaceable toward us?  Then  .... [the Tetrarchs] passed their time in tranquil peace, in festivals and public games and most joyful pleasures and cheer.  While thus their authority was ... increasing day by day, suddenly they changed their peaceful attitude toward us, and began an implacable war” (‘Historia Ecclesiastica’, 8:13: 9-10).

The sections below describe the stages in which this ‘war’ proceeded prior to Diocletian’s abdication in 305 AD.

Purge of the Court and the Army (302 AD ?)

Diocletian took what seems to have been his first formal action against Christians while he was in Antioch (in modern Syria), which was his main residence in the period 299-302 AD.  According to Lactantius, this was prompted by the complaints of pagans in Diocletian’s entourage that were aimed at their Christian colleagues:

  1. “Diocletian ... was a searcher into the future and, during his residence in the east, he began to slay  [animals] so that he might obtain from their livers a prognostication of events; and while he sacrificed, some attendants of his, who were Christians, ... put the immortal sign [i.e. made the sign of the Cross] on their foreheads .  At this, the ... rites [of divination were] interrupted.  The haruspices trembled, unable to find the looked-for signs on the entrails of the victims.  They frequently repeated the sacrifices, in case the [earlier ones] had been unpropitious; but the victims ... afforded no tokens for divination.  At length Tages, the chief haruspex ... said, ‘There are profane persons here, who obstruct the rites’.  Then Diocletian, in furious passion [took two actions]:

  2. -[He] ordered not only all who were assisting at the holy ceremonies, but also all who resided within the palace, to sacrifice and, if they refused, to be scourged. 

  3. -And further, he sent letters to the commanding officers [throughout the army], demanding that all soldiers should be forced to the like impiety [i.e. to sacrifice], under pain of being dismissed from the service. 

  4. Thus far his rage proceeded; but at that season he did nothing more against the law and religion of God.  After an interval of some time he went to winter in Bithynia [at Nicomedia, modern İzmit, on the coast of the Sea of Marmara in Turkey] ... ” (‘De Mortibus Persecutorum’, 10: 1-6).

The requirement that courtiers and serving soldiers should sacrifice was a means of determining whether or not they were committed Christians (i.e. whether their private beliefs impeded their ability to participate in the civic ritual that was seen as fundamental to the health of the State). 

According to the ‘Chronicle’ of St Jerome, in the 16th year of Diocletian’s reign:

  1. “Veturius, magister militiae (Master of the Soldiers), persecuted the Christian soldiers, the persecution against us [i.e. the more general persecution of Christians] beginning little by little from just that time.”

Jerome based his ‘Chronicle’ on a now-lost precursor by Eusebius.  However, in his surviving and more detailed account of these events, Eusebius himself was unable or unwilling to name the relevant military commander:

  1. “For when the commander, whoever he was, began to persecute the soldiers, separating into tribes and purging those who were enrolled in the army, giving them the choice:

  2. -either by obeying, to receive the honour that belonged to them; or ...

  3. -if they disobeyed ... , to be deprived of [that honour];

  4. a great many soldiers of Christ’s kingdom, without hesitation, instantly preferred the confession of [Christ] to the seeming glory and prosperity that they [had previously been] enjoying” (‘Historia Ecclesiastica’, 8:4:3).

St Jerome’s Veturius is otherwise unknown and his putative rank is anachronistic.  David Woods (referenced below) suggested that the name had been derived from a misunderstood place-name, and that the commander in question might have been an unnamed prefect of the legio IV Martia stationed at Betthorus (a Roman fort built in ca. 300 AD in modern Jordan, which was close to Eusebius’ see of Caesarea in Palestine).   St Jerome’s chronology placed it before the final Roman victory against the Persians in 298 AD (see below).

The date of the introduction of this purge (which was, at this stage, restricted to the imperial court and the army) has been variously assigned by scholars (referenced below) to:

  1. 297 AD (Leadbetter, at p 129), who suggested that Veturius’ programme was a response to Diocletian’s command and relied on St Jerome’s chronology;

  2. 299 AD (Barnes, 1981, at pp 18-9; Davies, at  pp 91–3; and Burgess, who re-dated Veturius’ programme by correcting St Jerome); and

  3. 302 AD (Potter, at note 17, p 649 in the 2014 edition; and DePalma Digeser, 2000, at p 1).

Persecution of the Manichaeans (302 AD ?)

This campaign against the Manichaeans, an originally Persian religious sect that combined elements of the Jewish, Christian, and Persian Zoroastrian religions, is known from a rescript that Diocletian issued from Alexandria in response to a request from Julianus, who was then  proconsul of Africa.  The rescript was preserved in the ‘Collatio Legum Mosaicarum et Romanorum, (Collation of the Laws of Moses and the Romans), a compilation of source material made in the 4th century that was intended to document the similarities and differences between Roman and Jewish law.  It is translated by Doug Lee (at 3.2, p 66), discussed by Simon Corcoran (at p 35), and dated by Timothy Barnes (1982, p 55 and note 41) - all referenced below.  (See also this translation online by Christopher Haas).

The importance of this document in the present context is that it explains why new and foreign religions were deemed to pose a threat to the Empire that was sufficient to merit persecution:

  1. “But the immortal gods ... have deigned to dispose and arrange matters so that good and true principles should be approved and fixed by the wisdom and constant deliberation of many good, eminent, and very wise men.  It is not right to oppose or resist these principles, nor ought the age-old religion be disparaged by a new one.  For it is the height of criminality to re-examine doctrines once and for all settled and fixed by the ancients, doctrines which hold and possess their recognised place and course.  Wherefore it is our vigorous determination to punish the stubborn depraved minds of these most worthless people .... [who might otherwise] try ... to infect men of a more innocent nature, namely the temperate and tranquil Roman people, as well as our entire Empire with what one might call their malevolent poisons .... [These included] all types of offences against the statutes ”.

In other words, the new religions threatened both:

  1. to displease the ancient deities that protected the Empire; and

  2. to undermine respect for its traditions and its laws.

The penalties imposed were draconian:

  1. The offending religious leaders and their sacred texts were to be burned.

  2. Their followers were to be executed, and their property confiscated.

  3. Persons of rank might be excused execution, but they faced confiscation and forced labour in “the Phaenensian or Proconnesian mines” (the marble quarries of Proconnesus (Marmara Island, off Turkey) or the copper mines at Phaeno in Palestine).

These measures were not sufficient to destroy the sect: for example, the future St Augustine had been a Manichaean in Africa prior to his conversion to Christianity in 386 AD.

Edict of Persecution of Christians (24th February 303 AD)

Lactantius continued his account:

  1. “After an interval of some time, [Diocletian] went to winter in Bithynia [at Nicomedia]; and presently Galerius Caesar came thither, inflamed with furious resentment, and purposing to excite the inconsiderate old man [Diocletian] to carry on that persecution which he had begun against the Christians” (‘De Mortibus Persecutorum’, 10-6).

Timothy Barnes (referenced below, 1982, at pp 55-6) identified this as the winter of 302/3 AD.  According to Lactantius:

  1. “... during the whole winter, Diocletian and Galerius held councils together, at which no one else assisted; and it was the universal opinion that their conferences respected the most momentous affairs of the Empire” (‘De Mortibus Persecutorum’, 11:3). 

As Bill Leadbetter (referenced below, at p 131), it is most unlikely that Lactantius’ perception that the need for further measures against Christians was the main subject of these discussions is almost certainly incorrect.   Nevertheless, they were certainly on the agenda, as subsequent events would show.

Lactantius described a series of lectures that were held at Diocletian’s court at this time, which addressed the perceived errors inherent in Christian belief:

  1. “When I was teaching rhetorical learning in Bithynia, having been called there [from Africa by Diocletian] ... at the same time the temple of God was overthrown, there were living at the same place two men who insulted the truth as it lay prostrate and overthrown ... :

  2. -[One of them] professed himself the high priest of philosophy .... [He] vomited forth three books against the Christian religion.

  3. -Another, who was then of the number of the judges, and who was especially the adviser of enacting persecution, wrote on the same subject with more bitterness .... He composed two books:

  4. not against the Christians, lest he might appear to assail them in a hostile manner; but

  5. [addressed] to the Christians, so that he might be thought to [point out their errors] with humanity and kindness” (‘Divine Institutes’, V:2).

Elizabeth DePalma Digeser (referenced below, at p 5) identified these as, respectively:

  1. Porphyry of Tyre, an eminent philosopher (an identification defended, for example, by Bill Leadbetter, referenced below, at pp 150-1, note 118); and

  2. Sossianus Hierocles, the governor of Bythnia. 

However, as Bill Leadbetter (referenced below, at p 120) pointed out:

  1. “The intellectual coterie that [Digeser] correctly discerns as gathering in Nicomedia in the winter of 302/3 AD did not make the ultimate decisions.  They can be seen either:

  2. -as lobbying [Diocletian] to persecute, as as Digeser seems to suggest; or

  3. -as presenting an intellectual apologia for a programme of persecution already decided upon”.

Lactantius was clear that, whatever the contributions of these polemists, the most important person in shaping the policy was Galerius.  He therefore imagined the tenor of the conversations that had taken place on this subject during the private meetings that Galerius had with Diocletian at this time:

  1. “The old man [Diocletian] long opposed the fury of Galerius, and showed how pernicious it would be to raise disturbances throughout the world and to shed so much blood; that the Christians were wont with eagerness to meet death; and that it would be enough for him to exclude persons of that religion from the court and the army [as above].  Yet he could not restrain the madness of [Galerius].  He resolved, therefore, to take the opinion of his friends ... and, therefore, a few civil magistrates and a few military commanders were admitted to give their counsel; and the question was put to them according to priority of rank. 

  2. -Some, through personal ill-will towards the Christians, were of opinion that they ought to be cut off, as enemies of the gods and adversaries of the established religious ceremonies. 

  3. -Others thought differently, but, having understood the will of Galerius, they ... concurred in the opinion given against the Christians. 

  4. Yet not even then could [Diocletian] be prevailed upon to yield his assent.  He determined above all to consult his gods; and to that end he despatched a soothsayer to inquire of Apollo at Miletus, whose answer was such as might be expected from an enemy of the divine religion.  So Diocletian was drawn over from his purpose ... , yet still he attempted to observe such moderation as to command the business to be carried through without bloodshed; whereas Galerius would have had all persons burnt alive who refused to sacrifice” (‘De Mortibus Persecutorum’, 11: 4-8).

Lactanius then described how Diocletian put his eventual decision into effect:

  1. “A fit and auspicious day was sought out for the accomplishment of this undertaking; and the festival of the god Terminus, celebrated on the 7th of the kalends of March [23rd February], was chosen ... in the 8th consulship of Diocletian and 7th of Maximian [303 AD]” (‘De Mortibus Persecutorum’, 12:1).

The first intimation of what was about to happen was the destruction of a church in Nicomedia:

  1. “When that day dawned, ... while it was yet hardly light, the Prefect, together with the chief commanders, tribunes, and officers of the treasury, came to the church in Nicomedia and ... searched everywhere for an image of the Divinity.  The books of the Holy Scriptures were found, and  committed to the flames; the utensils and furniture of the church were abandoned to pillage: all was rapine, confusion, tumult.  That church, situated on rising ground, was within view of the palace; and Diocletian and Galerius stood, as if on a watch-tower, disputing long whether it ought to be set on fire.  ... [When they decided against that course of action], the Praetorian Guards came in battle array ... and levelled that very lofty edifice with the ground in a few hours”. (‘De Mortibus Persecutorum’, 12)

Lactantius then reported that the formal Edict was published at Nicomedia on the following day. 

Eusebius described the content of the Edict:

  1. “It was in the 19th year of the reign of Diocletian, in the month ... called March by the Romans, when [Easter] was near at hand, that royal Edicts were published everywhere, commanding that the churches be levelled to the ground and the Scriptures be destroyed by fire, and ordering that those who held places of honour be degraded, and that the [imperial] household servants, if they persisted in the profession of Christianity, be deprived of freedom” (‘Historia Ecclesiastica’ 2:4)

Thus, Simon Corcoran (referenced below, 1996, at p 180) summarised that it mandated:

  1. “... the razing of churches, the surrender of scriptures for burning, and the loss of civil rights, especially for people of high status.  Caesariani [freedmen in imperial service] were to be re-enslaved”.

Thus, the Edict was principally designed to destroy the established Church by driving it underground and by deterring men of ambition from an overt association with it.

Lactantius claimed that Galerius arranged for a programme of arson at the imperial palace which he sought to blame on Christians so that Diocletian would be induced to impose yet harsher measures.  However, the future Emperor Constantine, who was an eyewitness, did not mention any claim of arson:

  1. “Diocletian, however, after the display of relentless cruelty as a persecutor, evinced a consciousness of his own guilt and owing to the affliction of a disordered mind ... passed the residue of his life in continual dread of the lightning's strike.  Nicomedia attests the fact; eyewitnesses (of whom I myself am one) declare it.  The palace, and the Emperor's private chamber were destroyed, consumed by lightning, devoured by the fire of Heaven” (Oration to the Assembly of the Saints’, 25: 1-4).

Returning to Lactantius’ account, when Galerius’ first arson attack failed to have the desired effect, he tried again.  Then,:

  1. “Galerius, who in the middle of winter had prepared for his departure, suddenly hurried out of the city, protesting that he fled to escape being burnt alive” (‘De Mortibus Persecutorum’, 14-6).

Timothy Barnes (referenced below, 1982, at pp 64) identified the date of Galerius’ departure for the Danube as March 303 AD.  Bill Leadbetter (referenced below, at p  101) discounted that he was driven away by fear of fire in the palace, observing that:

  1. “... [Galerius was more probably] summoned by the more urgent flames of war [on the Danube]”.

Later Legislation against Christians

Eusebius made two references to a second edict that apparently followed soon after the first:

  1. -“... not long after [the Edict of February 303 AD], as persons in the country called Melitene [in modern Turkey] and others throughout Syria attempted to usurp the government, a [second] royal edict directed that the rulers of the churches everywhere should be thrown into prison and bonds.  What was to be seen after this exceeds all description.  A vast multitude were imprisoned  ... and the prisons everywhere, which had long before been prepared for murderers and the robbers of graves, were filled with [Christian] bishops, presbyters, deacons, readers and exorcists, so that room was no longer left in them for those condemned for crimes”.

  2. -“[This second edict commanded] ... that all the rulers of the churches everywhere should first be thrown into prison and afterwards, by every artifice, be compelled to sacrifice” (‘Historia Ecclesiastica’, 8:2:5). 

Thus, it seems that Diocletian was prompted to imprison leading Christians after what was perhaps an unexpected and possibly localised unrest when the terms of the first edict were put into effect.  Simon Corcoran (referenced below, 1996, at p 181) dated this second edict to summer 303 AD.

Eusebius suggests that officials generally tried to empty the prisons “by every artifice”, which probably included persuading prisoners to go through the motions of pagan sacrifice in order to secure release.  Pressure on them to do so seems to have increased during the general amnesty that was granted to prisoners at the time of the vicennnalia (November 303 AD).  Simon Corcoran (as above, at p 181) suggested that a specific edict to this effect directed at Christians was issued at about this time.  Unfortunately, it seems that it backfired in some cases, when committed Christians refused to dissemble and instead invited martyrdom.

  1. -“And as other decrees followed the first, directing that those in prison, if they agreed to sacrifice, should be permitted to depart in freedom, but that those who refused should be harassed with many tortures, how could any one, again, number the multitude of martyrs in every province,  and especially of those in Africa, Mauritania, Thebais and Egypt (‘Historia Ecclesiastica’, 8:6:10)

  2. -“At last, the 20th anniversary of the Emperor being near, when, according to an established gracious custom, liberty was proclaimed everywhere to all who were in bonds [many Christian prisoners secured release from prison in Antioch.  Only one, Romanus, a deacon of Caesarea, who had been imprisoned for obstructing the destruction of churches there and had already had his tongue cut out on Diocletian’s direct orders, resisted] and had both his feet stretched over five holes in the stocks, and, while he lay there, he was strangled and was thus honoured with martyrdom as he desired.” (‘Martyrs of Palestine’, 2:4).

Simon Corcoran (as above, at p 182) then pointed to references by (respectively) Eusebius and Lactantius to a fourth persecution Edict, which he dated to early 304 AD:

  1. -“In the course of the second year [of the official persecution], the persecution against us increased greatly” (‘Martyrs of Palestine’, 3:1). 

  2. -“And now Diocletian raged, not only against his own domestics, but indiscriminately against all; and he began by forcing his daughter Valeria and his wife Prisca to be polluted by sacrificing.  Eunuchs, once the most powerful, and who had chief authority at court and with the Emperor, were slain.  Presbyters and other officers of the Church were seized, without evidence by witnesses or confession, condemned, and together with their families led to execution.  ... Nor was the persecution less grievous on the rest of the people of God; for the judges, dispersed through all the temples, sought to compel every one to sacrifice.  The prisons were crowded; tortures, hitherto unheard of, were invented; and, in order to ensure that justice was not inadvertently administered to a Christian, altars were placed in the courts of justice, hard by the tribunal, that every litigant might offer incense before his cause could be heard.  ... Mandates also had gone to Maximian Herculius and Constantius, requiring their concurrence in the execution of the edicts; for in matters even of such mighty importance their opinion was never once asked.  [Maximian], a person of no merciful temper, yielded ready obedience, and enforced the edicts throughout his dominions of Italy.  Constantius, on the other hand, lest he should have seemed to dissent from the injunctions of his superiors, permitted the demolition of churches - mere walls, and capable of being built up again - but he preserved entire that true temple of God, which is the human body (De Mortibus Persecutorum’, 15).

It seems to have been at this stage that the persecution was extended to Christians more widely, rather than simply those in the army and at court and those holding official positions in the Church.

Abdication of the Augusti (305 AD)



RIC VI Trier 35

Vicennalia (303 AD)

Diocletian seems to have begun thinking in earnest about retirement at the time of his vicennalia, the celebration at the start of of his twentieth year in power, which (as noted above), he celebrated in Rome on 20th November 303 AD (as described in the page on Diocletian, Maximian and Rome).  This was an almost unprecedented event: no Emperor had ruled long enough to celebrate his 20th anniversary since Antoninus Pius (138-61 AD).   As explained above, Maximian’s official date of accession had been altered in 293 AD so that it coincided with that of Diocletian, so he naturally shared in the celebration. 

It is possible that Diocletian used the opportunity of this time spent with Maximian to extracted from his colleague an oath to the effect that he would join Diocletian in abdicating in due course.  This, at least is the import of a passage in Panegyric VI (translated into English in Nixon and Rodgers, referenced below), which was delivered in 310 AD to the then Emperor Constantine in the aftermath of his betrayal by Maximian.  The panegyrist looked back bitterly on an earlier vow that Maximian had given and subsequently broken:

  1. “So, this fellow [Maximian] ... regretted having sworn an oath to [Diocletian] in the temple of Capitoline Jupiter” (‘De Mortibus Persecutorum’, 15:6).

It is clear from the context that this putative oath had involved Maximian’s abdication, and the most likely point at which any such oath could have been sworn in the Capitoline Temple was surely at the time of the vicennalia

There is numismatic evidence that supports the literary evidence above: Carol Sutherland (RIC, referenced below, at p 145) pointed out:

  1. “Whatever Diocletian’s plans for retirement, they were certainly not widely published [during the vicennelia celebrations]:  they were perhaps first presaged by the TEMPORUM FELICITAS/ CAESS XIII COSS V multiple of Constantius in the first four months of 305 AD.”

This gold multiple (RIC VI Trier 35, illustrated above) showed two Emperors, almost certainly Diocletian and Maximian, sacrificing outside a temple that Philip Hall (referenced below, at p 26) identified as the Capitoline Temple (because of its six columns, of which four are depicted, and the oak wreath in its pediment).  Constantius also used this reverse design on another coin (RIC Trier 617), which he minted after his elevation to the rank of Augustus.  As Philip Hill observed:

  1. “The earlier coin ... might have been struck ready for distribution on New Year’s Day [of 305 AD] when the Caesars [Constantius and Galerius] entered into the Consulship.  The later piece ... would have been struck in readiness for 1st May [305 AD}, when Constantius [like Galerius] was promoted”.

This close association of:

  1. the motif of two Emperors sacrificing outside what is almost certainly the Capitoline Temple; and

  2. the elevation of Constantius and Galerius to the rank of Augustus;

is surely circumstantial evidence that the abdications that led to their elevation had been vowed at this temple during the vicennalia.

Further evidence that the abdication was pre-planned is found in another panegyric (Panegyric VII, translated into English in Nixon and Rodgers, referenced below, which was delivered in 307 AD at Constantius’ court, probably at Trier, in Maximian’s presence), in which the panegyrist asserted that Maximian had agreed to abdicate in 305 AD:

  1. “... [in] adherence to a plan [that had been] long since resolved upon ... by you both [i.e. by Maximian himself and Diocletian] ...” (9:2).

Finally, as Bill Leadbetter (referenced below, at p 139) pointed out:

  1. “Diocletian’s retirement home [i.e. the extensive villa complex that he built at [Spalatum, modern Split, in Croatia], which included his mausoleum] was planned well in advance of his abdication in 305 AD.  ... it follows logically that so was Diocletian’s retirement itself.  The very existence of the Split palace itself is firm evidence that Diocletian’s retirement was a contemplated and deliberate  act of policy [albeit that the precise date at which he took the decision is unknown].”

Diocletian’s Illness (304-5 AD)

It seems that Diocletian had initially planned to stay in Rome long enough to celebrate the start of the year of his 9th Consulship there, but that he subsequently changed his mind.  According to Lactantius:

  1. “... suddenly [Diocletian], unable to bear the Roman freedom of speech, peevishly and impatiently burst away from the city.  The kalends of January [i.e. the start of the following year] approached, at which day the Consulship was to be offered to him for the 9th time: yet, rather than continue 13 days longer in Rome, he chose that his first appearance as Consul [in 304 AD] should be at Ravenna. ” (‘De Mortibus Persecutorum’, 17:2-3).

Diocletian presumably reached Ravenna in time to celebrate his 9th consulship on 1st January.  He then set out for Nicomedia, but was apparently slowed down considerably by a deterioration in his health.  Thus, according to Lactantius:

  1. “Having ... begun his journey in winter [of 303/4 AD] amidst intense cold and incessant rains, he contracted a slight but lingering disease: it harassed him without intermission, so that he was obliged for the most part to be carried in a litter.  Then, at the close of summer [of 304 AD], he made a circuit along the banks of the Danube, and so came to Nicomedia.  [He issued a rescript there, CJ 3 28 26, on 28th August 304 AD.]  His disease had now become more grievous and oppressing; yet he caused himself to be brought out at the conclusion of the 20th year of his reign, in order to dedicate the circus that he had erected [for the occasion].  Immediately he grew so languid and feeble that prayers for his life were said to all the gods.  Then suddenly, on the ides of December [13th December 304 AD], sorrow and weeping were heard in the palace ... and a report of the death, and even of the burial, of Diocletian circulated: but early on the morrow, it was suddenly rumoured that he still lived.  ... Nevertheless there were those who suspected that his death was to be kept secret until the arrival of Galerius Caesar, lest ... the soldiery should attempt some change in the government; and this suspicion grew so universal that no-one would believe the Emperor alive until, on the kalends of March [1st March 305 AD], he appeared in public, but so wan ... as hardly to be recognised.  ... [A]lthough he recovered to an extent, he never attained to perfect health again, for he became disordered in his judgment, being at certain times insane although at others of sound mind” (‘De Mortibus Persecutorum’, 17: 4-10).

Lactantius tended to exaggerate the suffering of Emperors like Diocletian who had persecuted Christians: indeed, his central thesis was that their actions in this respect had provoked divine retribution.  Nevertheless, he could hardly assert that Diocletian had been feared dead in December 304 AD, and had not appeared in public thereafter until the following March, unless something of the sort had actually happened.

Abdication (1st May 305 AD)

Eutropius gave an informative (if strangely ‘matter of fact’) account of the abdication, which he thought was simply a consequence Diocletian’s advanced age:

  1. “But when Diocletian, as age bore heavily upon him, felt himself unable to sustain the government of the Empire, he suggested to [Maximian] Herculius that they should both retire into private life, committing the duty of upholding the State to more vigorous and youthful hands.  His colleague [Maximian] reluctantly complied with this suggestion.  Both of them, on the same day, exchanged the robe of Empire for an ordinary dress: Diocletian at Nicomedia; [Maximian] Herculius at Milan; ....

  2. -[Diocletian] then retired to Salonae [Salona,  where (as mentioned above) his new and as yet unvisited palace awaited him]; and

  3. -[Maximian retired] into Lucania [in southern Italy]” (‘Breviarium historiae Romanae’ 9:27).

The precise date of the abdication can be calculated from a passage by Lactantius, which referred to the later battle between Maximinus, who had been appointed as Caesar on the day of the abdication, and his rival Licinius in 313 AD:

  1. Licinius resolved to give battle on the kalends of May because, precisely eight years before, [Maximinus] had received the dignity of Caesar” (‘De Mortibus Persecutorum’, 46:8).

Thus Maximinus had become Caesar, and hence Diocletian and Maximian had abdicated, on 1st May 305 AD.

In his long and presumably speculative account of the abdication, Lactantius explained that the old Augustus had had no choice in the matter, since Galerius (whom he seems to have hated with particular venom) had demanded that they should either do so or face civil war:

  1. “Within a few days [of Diocletian’s public appearance on 1st March 305 AD], Galerius Caesar arrived [at Nicomedia], not to congratulate [Diocletian] on the re-establishment of his health, but to force him to resign the Empire.  Already [presumably during a recent visit to Milan], he had urged Maximian Herculius to the like purpose, and by the threat of civil wars terrified the old man into compliance; and he now assailed Diocletian.   [After a period of argument, Galerius threatened that] if Diocletian would not resign, then he [Galerius] must consult his own interests, so as to remain no longer [the most junior of the Tetrarchs] ... Diocletian already knew, from letters he had received from Maximian Herculius, of everything that Galerius had [said to him] and also that he [Galerius] was augmenting his army [presumably for civil war, should the Augusti refuse to go quietly].  Now, on hearing this discourse [from Galerius himself], the spiritless old man burst into tears and said: ‘Be it as you will’” (‘De Mortibus Persecutorum’, 18: 1-10).

This view - that Galerius had forced both Diocletian and Maximian to abdicate against their wishes -  is difficult to sustain: as Bill Leadbetter (referenced below, at p 137) argued:

  1. “[Galerius] could not have brought any instrument of state into play against Diocletian even had he been willing to [do so].  He simply lacked the prestige to carry it off.   ... Furthermore, the act itself would have been impious, a violation of the charismatic and family relationship that Diocletian had been careful to establish”.

In other words, Galerius’ putative threat of civil war would have been hollow: both he and his erstwhile colleagues and potential adversaries would have known that:

  1. he would have been highly unlikely to have succeeded; and

  2. even had he done so, it would have involved the destruction of his own claim to legitimacy, inherited from Diocletian, which was the key to his future status and security. 

Lactantius’ difficulty in believing that Diocletian’s abdication was voluntary was probably shared by many of his contemporaries, albeit that no other surviving source claimed that Galerius had forced it upon him.  As noted above, Eutropius thought that Diocletian’s decision was simply a consequence of his advanced age.  Eusebius (at least in one of his accounts) put it down to Diocletian’s poor health, hinting at an associated mental incapacity:

  1. “But, when the second year of [the persecution of Christians] was not yet past, a revolution took place in the entire government and overturned everything.  For a severe sickness came upon [Diocletian], by which his understanding was distracted; and, together with [Maximian], he retired into private life.  Scarcely had he done this when the entire Empire was divided; a thing which is not recorded as having ever occurred before” (‘Historia Ecclesiastica’, 8:13: 10-11).

These theories are all unsatisfactory for two main reasons:

  1. they conflict with the evidence (above) that Diocletian had made his decision before November 303 AD; and

  2. they do not explain why Diocletian insisted that the reluctant, younger and apparently healthy Maximian to join him in relinquishing power.  (It is a tribute to his charisma and his natural pre-eminence within the Tetrarchy that he was able to do so). 

Zonaras suggested that the decision of the Augusti was prompted by desperation at the failure of this campaign of persecution:

  1. In the twentieth year [sic] of Diocletian’s reign, by an agreement between both the Emperors, they [Diocletian and Maximian] set aside imperial rule, saying in public that they had been wearied by the weight of affairs.  However they concealed the actual contents of their hearts, agreeing to put aside the Empire out of desperation, since they were unable to prevail over the Christians or to extinguish the herald of Christ, so they chose to give up imperial rule” (‘Epitome Ton Istorion’, 12:33).

This suggestion has little to commend it.  However, it is possible that campaign against the Christians (like that against the Manichaeans) started when it did because Diocletian was already planning his abdication at that time.  For the policy to be successful, Diocletian would need to rely on the theology of the divine patronage of the Augusti in order to demonstrate the legitimacy of his chosen successor.  But, as Bill Leadbetter (referenced below, at p 130) pointed out:

  1. “Christianity’s rejection of the traditional pantheon implied a rejection of imperial theology; of the Augusti as Iovius and Herculius; and of the implied nexus between private piety and public religion.”

In rejecting Jove, Christians could not avoid undermining Diocletian’s central claim to legitimacy and, more importantly (given Diocletian’s natural ascendancy by that time), the legitimacy of his chosen successor.  

In the end, Diocletian’s decision to abdicate probably confounded public opinion at the time.    Even Eusebius, in his second account of the event, admitted that he had no idea as to the reasoning behind it:

  1. “... the older Emperors [Diocletian and Maximian], for some unknown reason, resigned their power; and this sudden change took place in the first year after their persecution of the churches” (‘Vita Constantini’, 1:18:2).

The most obvious solution to the conundrum is to accept that the joint abdication was pre-planned and thus a matter of policy: Diocletian presumably decided that this action would allow him to arrange for an uncontested succession, thereby ensuring that the internal stability that he had created for the Empire would survive him.

Read more:

RIC VI: See Sutherland (1967) below

Corcoran, “Diocletian”, in

  1. A. Barrett (Ed.), “Lives of the Caesars”, (2009) London pp 228-54

W. Leadbetter, “Galerius and the Will of Diocletian”, London 2009

E. Depalma Digeser, “An Oracle of Apollo at Daphne and the Great Persecution", Classical Philology, 99 (2004) 57-77

P. Kiernan, “Imperial Representation under Diocletian and the Tetrarchy”, (2004) ) Thesis of the University of Cincinnati

D. Potter, “The Roman Empire at Bay, 180–395 AD”, (2004, second edition 2014) Abingdon

R. Rees, “Diocletian and the Tetrarchy”, (2004) Edinburgh

P. Porena, “Le Origini della Prefettura del Pretorio Tardoantica”, (2003) Rome

  1. The two inscriptions mentioned above are discussed in Chapter II.

D. Woods, “Veturius' and the Beginning of the Diocletianic Persecution”, Mnemosyne 54 (2001) 587-91

E. DePalma Digeser, “The Making of a Christian Empire: Lactantius and Rome”, (2000) Ithaca, New York

A. Lee, “Pagans and Christians in Late Antiquity: A Sourcebook”, (2000) London

R. Burgess, “The Date of the Persecution of Christians in the Army”, Journal of Theological Studies, 48 (1997) 471–504

S. Corcoran, “The Empire of the Tetrarchs: Imperial Pronouncements and Government (284-324 AD)”, (1996, reprinted 2007) Oxford 

C. E. V. Nixon and B. S. Rodgers, “In Praise of Later Roman Emperors: The Panegyrici Latini”, (1994) Berkeley

A. Chastagnol, “Un Nouveau Préfet du Prétoire de Dioclétien: Aurelius Hermogenianus”, Zeitschrift für Papyrologie und Epigraphik, 78 (1989), 165-8

P. Davies, “The Origin and Purpose of the Persecution of 303 AD”, Journal of Theological Studies, 40 (1989) 66–94

P. Hill, “The Monuments od Ancient Rome as Coin Types”, (1989) London

S. Williams, “Diocletian and the Roman Recovery”, (1985, second edition 1997) London

T. Barnes, “New Empire of Diocletian and Constantine”, (1982) Harvard

T. Barnes, “Constantine and Eusebius”, (1981) Harvard

M. Hendy, “Mint and Fiscal Administration under Diocletian, His Colleagues, and His Successors (305-24 AD)”, Journal of Roman Studies, 62 (1972) 75-82.

R. E. Smith, “The Regnal and Tribunician Dates of Maximianus Herculius”, Latomus 31:4 (1972) 1058-71

K. Erim et al. (Eds), “Diocletian's Currency Reform: a New Inscription from Aphrodisias”, Journal of Roman Studies, 61 (1971) 171-7

C. H. V. Sutherland, “Roman Imperial Coinage: Volume VI: From Diocletian’s Reform to the Death of Maximinus (294-313 AD)”, (1967, reprinted 1973) London

R. Lanciani, “Storia degli Scavi di Roma e Notizie Intorno le Collezioni Romane di Antichità: Volume I, 1000-1530”, (1902, reprinted 1998) Rome

R. Lanciani, “The Ruins and Excavations of Ancient Rome: a Companion Book for Students and Travelers”, (1897)

Diocletian (284-305 AD)

Diocletian's Rise to Power (284-5 AD)      Diocletian and Maximian (285-93 AD)

First Tetrarchy (293-305 AD)      Diocletian, Maximian and Rome (285-305 AD)

Military Campaigns: Maximian and Constantius  in the West (293-305 AD)

Military Campaigns: Diocletian and Galerius in the East  (293-305 AD)

Imperial Cult (285-305 AD)

Diocletian to Constantine (285-337 AD): Literary Sources 

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