Key to Umbria

Constantine’s Auctor Imperii

The nature of Constantine’s claim to legitimacy changed on a number of occasions in the early part of his reign:

  1. The first two phases in this development are described in the page on Constantine's Accession (306 AD):

  2. Following the death of his father, the senior Augustus Constantius, in July 306 AD, Constantine probably claimed the rank of Augustus, either on the basis of his alleged designation as such by his father or on the (more easily demonstrated) basis of his acclamation by Constantius’ army.

  3. Within a few months, he decided to accept the offer from Galerius (the new senior Augustus) of the rank of Caesar.

  4. In September 307 AD, when Maximian returned from retirement, Constantine entered into an alliance with him and with his son, Maxentius.  He accepted the rank of Augustus from Maximian and married Maximian’s daughter Fausta.  Galerius refused to accept this designation, which he probably regarded as treasonous.  These events are described in the page on Maximian's Herculian Dynasty (307-8 AD).

  5. In November 308 AD, Galerius prevailed on Diocletian to return briefly to public life and host a meeting now known as the conference at Carnuntum, in order to

  6. -persuade Maximian to return to retirement; and

  7. -ratify Galerius’ new imperial college,which had Licinius as the second Augustus.

  8. Galerius essentially offered to recognise Constantine as Caesar once more.  These events are described in the page on Galerius II (308-11 AD).  Constantine  stopped short of outright rejection of the designations made at Carnuntum, but he made it clear that he still regarded himself as Augustus, by right of his descent from divus Constantius, and carried on much as before.

Constantine recognised Maximian’s retirement, but continued to offer him residence in Gaul.  This relatively stable (if constitutionally unsatisfactory) situation changed in the summer of 310 AD, when Maximian attempted to seize power in Gaul and succeeded in attracting part of Constantine’s army to his cause.  Constantine marched against Maximian, captured him at Marseille, and either executed him or encouraged him to commit suicide.  (These events are described in the page on Constantine in Gaul (308-11 AD)). 

Whatever value Maximian had had as Constantine’s auctor imperii was obviously at an end.   His (probable) execution of Maximian might well  have hardened opinion against him and the loyalty of at least part of his army was in doubt.  He could have settled for the offer that had been on the table since Carnuntum, which left him as the most junior member of the imperial college (since his fellow-Caesar, Maximinus had been in post longer than he had).  He could not know that, in just a few more months, Maximinus would force the issue and Galerius would respond by designating the erstwhile Caesares  as Augusti.  He therefore adopted a more radical solution: he continued to ignore Galerius and instead reformulated this claim of legitimacy in his own right.

Fortunately, this response was captured in a panegyric (Panegyric VI, translated into English in Nixon and Rodgers, referenced below) that was delivered at his court at Trier, probably in the summer of 310 AD, while the shock of Maximian’s treachery was still palpable.  In it, the panegyrist:  

  1. expressed Constantine’s claim to legitimacy in terms of his descent from:

  2. his father, divus Constantius; and

  3. (in a passage that came as a surprise to the audience), their ancestor, divus Claudius (the Emperor Claudius II, 268-70 AD); and

  4. announced a recent vision of Constantine in which he (Constantine) had discovered that he enjoyed the divine patronage of Sol Invictus.

Constantine, Constantius and Claudius II

The panegyrist articulated Constantine’s reformulated claim to legitimacy as follows:

  1. “I shall begin with the divinity who is the origin of your family, of whom most people, perhaps, are unaware .... For an ancestral relationship links you to the deified Claudius, who was the first to restore the discipline of the Roman Empire when it was disordered and in ruins ... [Y]our imperial fortune descended to you from that renowned founder of your family. ... Furthermore, that ancient prerogative of your imperial house advanced your father himself, so that you now take your place on the highest rung ... the third Emperor after two rulers of your line .... ” (2).

The panegyrist concluded:

  1. “No chance agreement of men... made you Emperor: it is through your birth that you merited the Empire” (3:1).

Thus while Galerius had achieved imperium only through a “chance agreement of men” (or, in his case, of one man, Diocletian), Constantine had been born to rule. 

The panegyrist makes clear that this was the first time that the claim that Constantine’s family descended from the deified Emperor Claudius II had been made (at least in public).  The decision must have been Constantine’s, and he presumably took it because he needed to reinforce his claim to legitimacy at this particular moment of weakness.  Constantine’s status as the son of the deified Constantius was of limited use, which is why he had awaited the intervention of Maximian before styling himself Augustus.  However, if both Constantius and Constantine descended from divus Claudius, Constantine’s claim would be significantly strengthened (at least in some quarters).  

Claudius II was an excellent choice for the role of Constantine’s putative ancestor: relatively little was known about him, but what was known was likely to impress both the army and the Senate as well as the people of Gaul (whose first concerns were for a ruler who could protect them from barbarians and govern them well).  His relevant qualities are evident in the account of his reign by Eutropius (who presumably drew on sources that were widely available in Constantine’s time):

  1. “Claudius succeeded [Gallienus], being chosen by the soldiers, and declared Emperor by the Senate.  He defeated the Goths, who were laying waste Illyricum and Macedonia, in a great battle.  He was a frugal and modest man, strictly observant of justice, and well qualified for governing the Empire.  He was however carried off by disease within two years after he began to reign, and had the title of a god.  The Senate honoured him with extraordinary distinctions, insomuch that a golden shield was hung up to him in the Senate House and a golden statue erected to him in the Capitol” (‘Breviarium historiae Romanae’, 9:11). 

Perhaps even more importantly, among all of the Emperors who had been proclaimed by the army during the chaotic 50 years before the Tetrarchy, he had been one of only two that did not meet his end at their hands. 

Claudius II in the ‘Historia Augusta

The historiography of these developments is complicated by the biography of Claudius II in the ‘Historia Augusta, which was purported to have been written by one ‘Trebellius Pollio’, while Constantius was still Caesar (i.e. before 305 AD).  Thus, it began:

  1. “I have now come to the Emperor Claudius, whose life I must set forth .... out of respect for Constantius Caesar”. 

It included an account of the family ties between the two men:

  1. “Since we have now described Claudius’ achievements in war, we must record a few things .. concerning [his] kindred and the family ... [He, Claudius II, together with], Quintillus and Crispus, were brothers: Crispus had a daughter Claudia; and, of her and Eutropius, the noblest man of the Dardanian folk, Constantius was born” (13).

He went on to give Claudius II elements of the formal name of Constantius:

  1. “We can say with truth that Flavius Claudius, an emperor without peer upon earth, is raised to eminence not by any columns or statues but by the power of fame”.

  2. “Long may you live, Valerius ...”.

In fact, we know from coins that the full name of Claudius II was Marcus Aurelius Claudius, and he was never documented in his lifetime as either Flavius or Valerius Claudius. 

The ‘Historia Augusta’ is a notoriously misleading source (as explained in the page Introduction to the Historia Augusta on  Indeed, Ronald Syme (in 1974, reprinted in 1983 and referenced below) argued in no uncertain terms that the way in which this part of the life of Claudius II was written was the most persuasive evidence for the claim that its apparent date was a fabrication:

  1. “From the beginning, the biography [of Claudius II] occupied a frontal position in [deciding] the controversy about the authorship, purpose and date of the Historia Augusta.  Dessau, in 1889, exposed the genealogical fraud. ... the biographer Pollio, who purports to be writing  when Constantius was Caesar ... is condemned by his foreknowledge of the great secret disclosed [by the panegyrist, above] in 310 AD.  Nor was it conceivable that any writer under the Tetrarchy should proclaim that one of the two Caesars had an Emperor for an ancestor and was himself the destined progenitor of a line of Augusti”.

The tenor of the account suggests that it was actually written in or shortly after 310 AD, presumably with an eye to Constantine’s likely approval.

This deception seems to have misled later writers, although the alleged relationship between Claudius and Constantius varies.  Thus:

  1. “....Constantius is said to have been the grand-nephew of Claudius by a daughter” (Eutropius, ‘Breviarium historiae Romanae’, 9:22)

  2. “... Constantius .... was the son of the daughter of the previous emperor Claudius” (Zonaras, Epitome Ton Istorion’, 12:22).

Constantine and Sol Invictus


RIC VI Lugdunum (Lyon) 310, (309-10 AD)

The panegyrist explained that, as Constantine returned to Rome from his confrontation with Maximian at Marseille, the news of his imminent return had averted a barbarian incursion across the Rhine.  He reminded Constantine that ,when he had received this intelligence:

  1. “... you [Constantine] turned aside toward the most beautiful temple in the whole world, or rather, to [its] deity made manifest ... For you saw ... your Apollo, accompanied by Victoria, offering you laurel wreaths, each of which carried a portent of 30 years ” (21: 3-4).

The vision was pithily summarised by Sutherland and Carson (referenced below, at p 111):

  1. “ .... [Sol] appeared to Constantine , in company with Victoria, and with all omens of success”

Scholars generally identify the temple in which this vision occurred as the sanctuary and thermal spring of Apollo Grannus at Andesina (now Grand, in the Vosges district of eastern France, on the Roman road from Lyon to Trier). 

There is a vast literature on this vision, but there is little consensus regarding its precise significance.  Indeed, it has sometimes been doubted whether this account derived from Constantine himself or whether it was, for example, a product of the panegyrist’s imagination.  However, at the very least, Constantine must surely have recognised it as broadly accurate, since he obviously allowed the panegyrist to recount it so publicly.  

Sol, Patron of Claudius and/or Constantius (?)

C. E. V. Nixon (in Nixon and Rodgers, referenced below, at note 92) speculated that Constantine’s religious experience:

  1. “ ... took him back to the deity of his father and his ‘ancestor’ Claudius”.

If so, this would have been of considerable dynastic significance.  But can it be substantiated?  It is true that Sol had been widely revered in the 3rd century AD, particularly as one of the deities who made Emperors such as Claudius II and Constantius victorious.  However, the evidence that either of them regarded Sol as his particular patron is, at best, mixed.

Claudius II

Sol appeared on a proportion of the coins of most 3rd century Emperors.  However, Claudius II was by no means conspicuous in this respect, as demonstrated, for example, by Paul Stephenson (referenced below, at p 78) and Mark Smith (referenced below, at p 203). 

This is in sharp contrast to Claudius’ partner and successor, the Emperor Aurelian (270-5 AD), who had successfully re-introduced the cult to Rome following his victories in the east, building a temple to Sol Invictus instituting a prestigious priesthood (the pontifices Dei Solis) there.  Mark Smith (referenced below, at p 203) described the numismatic evidence for his profound veneration of Sol:

  1. “It has been argued with good reason that Aurelian was particularly devoted to Sol, as evident from both the quantity and the character of his coinage:  [in particular, on some of his coins] Sol, named as his ‘comes’ (RIC V.1  [????]) and ‘conservator’ (RIC V.1 272, 305), is depicted handing a globe to Hercules, Mars, and Jupiter, a significant measure of how Aurelian viewed the relative authority of these deities”.


The case for Constantius is more complex. In general terms, all of the original Tetrarchs minted coins that depicted Sol, but (like Mars) he was less important in this respect than Jupiter and Hercules.  The numismatic evidence does not suggest that Constantius was more devoted to Sol than his colleagues.  In particular, as Mark Smith (referenced below) pointed out that:

  1. “ ...not a single coin of Constantius Augustus [i.e., in 305-6 AD, when he had full control of his own coinage] depicts Constantius with  ... Sol.  He did, however, produce 11 issues with Hercules and 5 featuring Jupiter”. 

Similarly, Johannes Wienand (referenced below):

  1. “The evidence does not ... allow us to conclude that Sol was a protective deity exclusive to Constantius in the period of the first and second Tetrarchies” (my translation).

This does not exclude a personal (i.e. non-official) reverence for Sol Invictus on the part of Constantius.  There is perhaps evidence for this from the surviving writings of his grandson, the Emperor Julian, who was himself passionately devoted to to Helios (Sol):

  1. In Oration IV: Hymn to King Helios’ (362 AD), Julian contemplated how a man might enter the service of the God:

  2. “Now far the best thing is when anyone has the fortune to have inherited the service of the god, even before the third generation, from a long and unbroken line of ancestors ...”.

  3. Helmut Castritius (referenced below, at pp 29-30) argued that the passage related to Julian himself, and that the long and unbroken line of ancestors comprised of: Claudius II; Constantius; and Julius Constantius (Julian’s father).  However, Mark Smith (referenced below, at p 196) was unconvinced:

  4. “The ... reference [in the extract above] to three generations may or may not refer to Julian and his ancestors.  But even if [it does], it is not at all certain that the three ancestors were Claudius, Constantius, and Julius Constantius  Further, even granting that assumption, what do we learn about Constantius' religion?  Only that, in [this] obscure reference, Julian referred to the idea that Constantius honoured Helios; nothing appears [here] that induces us to believe that Julian considered Helios as Constantius' patron deity.”

  5. In ‘Oration VII: To the Cynic Heracleios’ (362 AD), Julian imagined a conversation between Zeus and Helios:

  6. “Zeus was moved with compassion and, addressing himself to Helios, he said: ‘O my son ..., are you still minded to resent the insolence of that arrogant and audacious mortal [Constantine?], who, by forsaking you, brought so many calamities on himself and his race? ... You see yonder thine own child [Julian himself]”(228-9).

  7. “Then mighty Helios took up the tale and said: ‘... Know [Julian] that a mortal frame was given to you so that you might discharge these duties.  For we desire, out of respect for your ancestor [Constantius ?] to cleanse the house of your forefathers [of Christianity ?]” (‘Oration VII, To the Cynic Heracleios’: 234).

  8. David Greenwood (referenced below, at pp 141-2) explained these somewhat opaque passages as follows:

  9. “From Julian’s perspective, Constantius I’s son Constantine was an apostate Herculian, who had abandoned the worship of Helios for the Christian God, whereas whereas Constantius I’s grandson, Julian [himself] would loyally serve Helios, the god of his grandfather.  Julian sought to supplant Constantine, whose apostasy from Helios he saw as the root of the Empire’s current troubles”.

  10. However, the argument can again be made (following Mark Smith, above) that, while Julius asserted here that Constantius had Helios’ respect, presumably because he had shown him appropriate veneration, he (Julian) did not go so far as to claim that Helios had been Constantius' patron deity.

Sol/ Apollo, Patron of Augustus

Barbara Saylor Rodgers (in 1980, reference below) made an important observation which she derived from the concluding part of the panegyrists’ account of Constantine’s vision:

  1. “[You, Constantine, also] saw and recognised yourself in the likeness of [the man] to whom the divine songs of the bards had prophesied that rule over the whole world was due ...” (21:5).

She suggested that the panegyrist meant here that Constantine also recognised himself as a new Octavian/ Augustus, identified in the ‘Aeneid’ as the long-awaited ruler of a golden age.  As Sutherland and Carson (referenced below, at p 111)”

  1. “Apollo was for Constantine, as for Augustus long ago, the god of bright and warm regeneration aswell as the god of fiery destruction.”

Like Augustus, Constantine was young and handsome, and his right to rule had passed to him from his deified father.  Augustus had ended the civil wars of the 1st century BC and then  presided as the sole ruler over a newly-united Empire: Constantine could therefore now expect that Apollo would ensure the victories that he needed in order to emulate Augustus’ achievement.  

Gallic Cult of Apollo

According to Caesar, who was writing in ca. 50 BC:

  1. “[The native people of Gaul] worship as their divinity Mercury in particular, and have many images of him, and regard him as the inventor of all arts.  They consider him the guide of their journeys and marches, and believe him to have great influence over the acquisition of gain and mercantile transactions. Next to him they worship Apollo, Mars, Jupiter and Minerva; respecting these deities they have for the most part the same belief as other nations: that Apollo averts diseases, that Minerva imparts the invention of manufactures, that Jupiter possesses the sovereignty of the heavenly powers; and that Mars presides over wars” (‘Commentarii de Bello Gallico’, VI:17).

Unfortunately, Caesar chose to give Roman names to the important local deities: thus we do not know the early name for the Gallic deity that averted disease, whom Caesar identified with Apollo.  However, following the advent  of the Romans, the cult seems to have prospered in its Roman guise.  This survey in the excellent website DEO MERCURIO gives an idea of its vibrancy and popularity.

As noted above, Constantine’s vision probably took place at the sanctuary and thermal spring of Apollo Grannus at Andesina (modern Grand).  ‘Grannus is one of a large number of epithets given to Apollo in Gaul (the webpage link above gives about 20).  In particular, the author refers to an inscription from Trier (CIL XIII 3635):

In h(onorem) d(omus) d(ivinae) [d]eo Apolli/n[i G]ra[n]no Phoeb(o) 

L(ucius) I[n]genuvius Pri/manu[s] ex voto p(osuit)


  1. “... identifies Apollo Grannus with Phœbus, the solar manifestation of the classical Apollo.”

A slightly later panegyrist (below) from Augustodunum (Autun) spoke of:

  1. “our Apollo, whose boiling waters punish perjuries—which ought to be especially hateful to you” (V: 21:7).

In short, in choosing Sol/ Apollo for his public patron, Constantine was probably tapping into an important strand of local religious practice and belief.

Sol, Patron of Constantine

It is entirely possible that Constantine had a genuine and profound religious experience on the way back from Marseille that convinced him that he enjoyed the patronage of Sol, with whose help he would restore the cohesion and prosperity of the Empire.  Any such private feelings are, however, irrelevant to history.  The important thing here is that Constantine chose to take his vision and its implications into the public domain in what seems to have been an energetic propaganda campaign.

The fortunate survival of Panegyric VI allows us to understand what the message of the campaign was in some detail, but the most important evidence for the energy with which it was propagated comes from Constantine’s coins.  Thus, Sutherland and Carson (referenced below, at p 111) observed:

  1. “The ‘vision’ of 310 AD was immediately followed by fundamental changes in Constantine’s [bronze coinage], which thereafter laid  immense emphasis on Sol - Invictus [invincible] and Comes [companion] of Constantine, together with Mars.”

Constantine now claimed his legitimacy from Sol, who had chosen him for the task of restoring the Empire.  In choosing Sol for this rôle, Constantine distanced himself from the “Jovian’ Galerius and the ‘Herculian’ (and now departed) Maximian.  As discussed above, the evidence does not support the suggestion that Sol had been the particular patron of Claudius II and Constantius.  However, there are a number of other factors that might have inspired the choice:

  1. Apollo/ Sol had been the patron of two earlier Emperors who had, indeed restored the Empire: Augustus and Aurelian.

  2. The cult of Sol was popular with the military and its priesthood was one of the most prestigious in Rome (attracting men at the height of their Senatorial careers).

  3. The cult of Sol/ Apollo seems to have been among the most important in Gaul.

However, if Constantine’s coinage is to be used to gauge the place that Sol had in his propaganda in ca. 310 AD, it is important to put his ‘Sol’ coins in the context of his coinage more generally.  Thus, Sutherland and Carson (referenced below, at pp 111-2) continued:

  1. “But, Constantine was aware of the traditional feelings of Rome and Italy, to which respect must be paid if, in liberating them, he was not to turn them into one more ulcer of dissension.  Together with his sudden flood of Sol and Mars types, there came a renewed emphasis on the PRINCEPS IUVENTUTIS  type. ... [This] probably served to suggest that it was the Senate of Rome from which the ultimate confirmation of his power would come.”

Read more:

‘RIC’ - see Sutherland (1967) below

D. Greenwood, “Crafting Divine Personae in Julian’s Oration 7”, Classical Philology, 109:2 (2014), pp. 140-p

J. Wienand, “Costantino e il Sol Invictus” in:

  1. Enciclopedia Costantiniana” (2013) Trecanni

P. Stephenson, “Constantine: Unconquered Emperor, Christian Victor” (2009)  London

M. Smith, “The Religion of Constantius I”, Greek, Roman and Byzantine Studies 38 (1997) 187-208

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

R. Syme, “The Ancestry of Constantine”, originally published in 1974, but reprinted in

  1. Historia Augusta Papers”, (1983) Oxford, pp 237-53

B. Saylor Rodgers, “Constantine's Pagan Vision”, Byzantion 50 (1980) 259-78

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

H. Castritius, “Studien zu Maximinus Daia”, (1969) Kallmunz


Galerius as Augustus II (308-11 AD)     Licinius (308-11 AD)     

Maxentius in Rome: (308-11 AD)   Maxentius' Public Works

Maxentius' Complex on Via Appia     Maxentius' Coins for Divus Romulus (309 AD)

Constantine in Gaul (308-11 AD)     Constantine, Divus Claudius and Sol Invictus

Consecrated Tetrarchs (306-11 AD)     Consecrated Tetrarchs: Mausoleum Coins

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

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