Porphyry bust of Galerius, from his palace in Romuliana (Gamzigrad)

National Museum Zaječar 

On 1st May 305 AD (as set out in the page on the First Tetrarchy), Diocletian took the unprecedented steps of abdicating, and of insisting that his colleague Maximian should also give up power.  Thus, according to Eutropius:

1. “Both [Diocletian and Maximian], 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;
   

3. - and [Maximian] into Lucania” (‘Breviarium historiae Romanae’ 9:27).
   

Second Tetrarchy (305-6 AD) 

Power now passed seamlessly from the erstwhile Augusti to their respective Caesares:

1. ✴Galerius succeeded Diocletian as Augustus in the east; and
   

2. ✴Constantius succeeded Maximian as Augustus in the west.
   

Eusebius, in particular, was anxious to stress that, after the abdication, Constantius became senior Augustus:

1. “... [Diocletian and Maximian], for some unknown reason, resigned their power ....  From that time, Constantius alone received the honours of chief Augustus, having been previously, indeed, distinguished by the diadem of the imperial Cæsars, among whom he held the first rank; but after his worth had been proved in this capacity, he was invested with the highest dignity of the Roman Empire, being named chief Augustus of the four who were afterwards elected to that honour” (‘Vita Constantini’, 1:18).
   

There is ample epigraphic evidence for this, which includes an inscription (AE 1961, 0240) from Tuscany that reproduced a a securely dated military diploma of 7th January 306 AD, in which Constantius is named first among the Augusti. 

Another inscription (CIL IX  5433) from Ascoli Piceno gives the full name of each of the four members of the new imperial college:

dd. nn. Fla/vio Valerio/ Constantio et Galerio M/aximiano

i/nvictis et cl/ementissimis/ Augg

et dd./ nn. Flavio V/alerio Seve/ro et Galeri/o Valerio M/aximino

no/bilissimìs ac/ beatissimis [Caesaribus]

To our lords Flavius Valerius Constantius and Galerius [Valerius] Maximianus,

unconquered and most merciful Augusti

and to our lords Flavius Valerius Severus and Galerius Valerius Maximinus

most noble and most blessed [Caesars]

The new Caesars are also recorded  by Aurelius Victor:

“”... Severus and Maximinus, natives of Illyricum, were appointed Caesars:

1. -[Severus] for Italy; and
   

2. -[Maximinus] for the regions that [Galerius] had held [as Caesar] (‘De Caesaribus’, 40:1)
   

As discussed below, each of the Caesars owed his primary allegiance to Galerius.  Therefore, although Constantius was nominally the senior Augustus and although Severus’ formal allegiance to him was signalled by his new name, Flavius Valerius Severus, the actual situation was the opposite.  Thus, as Bill Leadbetter (referenced below, at page 146) expressed it:

1. “Galerius was junior Augustus in name only.  [In the negotiations that had led to the formation of the new imperial college, he] had reached for and grasped the prize of supreme power in the Roman world”. 
   

Bill Leadbetter (referenced below, at page 160) observed that:

1. “It is reasonable and consistent with the evidence to identify the accession of Constantius and Galerius as the point at which the [complete] division [between their respective territories] occurred”.
   

In other words, Constantius was now pre-eminent in his own domains but isolated from the administration of the rest of the Empire.  The likely territorial division between the Augustii is illustrated in this excellent map from Ian Mladjov's Resources:

1. ✴Constantius governed his part of the Empire from his existing residence at Trier.  Timothy Barnes (referenced below, 1982, at p 197) provided evidence that Constantius added Spain to his territories at this point.  
   

2. ✴Galerius, who had by this time established his principal residence at Serdica (modern Sofia), also exercised authority over the two Caesars:
   

3. •Severus, who had replaced Maximian at Milan; and
   

4. •Maximinus, whose principal residence was at Antioch.
   

New Caesars

Flavius Valerius Severus

Unfortunately, nothing is known of Severus’ career before his appointment as Caesar.  According to Lactantius, when Galerius put him forward as his candidate for this post, Diocletian asked incredulously:

1. “Who?  That dancer, that habitual drunkard, who turns night into day and day into night”;
   

to which Galerius answered:

1. “He deserves the office [of Caesar], for he has proved himself a faithful paymaster and purveyor of the army” (‘De Mortibus Persecutorum’, 18: 12).
   

According to the ‘Origo Constantini Imperatoris’:

1. “Severus Caesar was low both in character and in origin, given to drink, and hence a friend to Galerius.  Accordingly Galerius made Caesars of him and of Maximinus [below] .... To this Severus were assigned: some cities of Pannonia; Italy; and Africa” (9).
   

According to Lactantius, when Severus died in 307 AD, : 

1. “He left a son, Severianus,  ... who accompanied [Maximinus] in his flight from the field of battle [against Licinius in 313 AD].  Licinius caused [Severianus] to be condemned and executed, under the pretence that, on the death of [Maximinus], he had intentions of assuming the imperial purple” (‘De Mortibus Persecutorum’, 50: 4-5).
   

Thus, Severianus must have been at least in his twenties in 313 AD, which suggests that Severus had been in his late thirties or early forties when he became Caesar.  This and the very fact of his appointment suggests that he had rendered considerable service to Galerius over a number of years.  Too much should not be made of his alleged short-comings, since the surviving accounts were all written by men who were inherently ill-disposed towards him.

As noted above, Severus acknowledged his formal subservience to Constantius by adopting his family name, becoming Flavius Valerius Severus.  There is no surviving evidence for his explicit use of Constantius’ signum, Herculius, although coins minted for him as Caesar at Aquileia and Ticinum (RIC VI: p 317, 47a from Aquileia; and p 287, 54a from Ticinum) identified him on the reverse as ‘Herculi Comiti’. 

Maximinus

Torben Christensen (referenced below, at p 12) deduced that Maximinus was probably about twenty when he became Caesar.  However, this might be an under-estimate: if the suggestion below is correct - that Maximinus joined the army as an ordinary recruit but was promoted to the imperial bodyguard in 293 AD, when Galerius became Caesar - he would more probably have been in his late twenties at the time of the abdication.  This is supported by the fact that Lactantius had described both Maximinus and Constantine as adulescens (a youth or young man), which suggests that  that they were similar in age and, as discussed below, Constantine was more probably in his mid thirties by this time.  

The discussion of the early life of Maximinus has to start with Lactanius’ imagined dialogue between Galerius and Diocletian, when Galerius nominated Maximinus as one of the new Caesars:

1. “Diocletian: ‘... but whom else do you suggest [apart from Severus, above]?’
   

2. Galerius: ‘Him’, and he pointed out Daia, a young man [who was] half-barbarian.
   

3. Now Galerius had lately bestowed part of his own [original] name on this youth, calling him Maximinus ....
   

4. Diocletian: ‘Who is [this person] whom you present?’
   

5. Galerius: “Adfinis meus (a relative of mine by marriage)"(‘De Mortibus Persecutorum’, 18: 13-4).
   

Two early sources identify Maximinus as Galerius’ nephew rather than as merely a relative by marriage:

1. ✴Zosimus:
   

2. “Three years after Diocletian died [sic], and the reigning Emperors, Constantius and [Galerius] declared Severus and Maximinus (who was nephew to Galerius), the Caesars, giving all Italy to Severus, and the eastern provinces to Maximinus” (‘Historia Nova’, 2:8:1).
   

3. ✴In the ‘Epitome de Caesaribus’:
   

4. “[Maximinus, who was a] scion of [Galerius’] sister [and who was] called by the name [Daia] before [he received] imperium, was a Caesar for 4 years, then an Augustus in Oriens for 3 years” (40:18).
   

Whatever their precise relationship, the fact that (at least according to Lactantius) Galerius renamed the erstwhile Daia prior to his appointment as Caesar was extremely significant in dynastic terms.  As Torben Christensen (referenced below, at p 16) pointed out:

1. “This was an official announcement that [the newly re-named Maximinus] was destined to assume a place in the leadership of the Imperial government.”
   

According to Lactantius, Maximinus had easily secured a rapid advancement through the ranks of the military:

1. “... lately taken from the tending of cattle in forests to serve as a scutarius (literally ‘shield-bearer’, probably serving in the infantry);
   

2. -continuo protector (immediately made one of the imperial bodyguard);
   

3. -mox tribunus (recently made a tribune); and
   

4. -next day Caesar (‘De Mortibus Persecutorum’, 19:6).
   

Thus, he seems to have joined up as an ordinary soldier.  His elevation soon after to the imperial bodyguard can plausibly be linked to Galerius’ accession as Caesar in 293 AD.  Like Constantine below), he had probably served under Galerius in the Sarmatian war in 302 AD.  His recent promotion to the rank of tribune at the time of the abdication was presumably also due to the patronage of Galerius.  He was probably still junior in rank to Constantine (who was, according to Lactantius, a tribune of the first order), and  Lactantius might well have been correct when he asserted that he had not previously come to Diocletian’s attention.

Maximinus was married at the time of his accession and perhaps already had a baby son.  Lactantius recorded the fate of the boy and that of his younger sister after Maximinus died in 313 AD, during his war with Licinius (mentioned above): 

1. “Licinius ... put to death Maximus, the son of [Maximinus], a boy eight years old, and also a daughter of [Maximinus], who was seven years old and had been betrothed to Candidianus” (‘De Mortibus Persecutorum’, 50: 6).
   

Thus, his two children had both been born in the period 305-7 AD.  The date of his daughter’s betrothal to Candidianus, Galerius’ illegitimate son (who was some 10 years her senior), is unclear.  It might well have occurred during Galerius’ lifetime, even though she was only about five years old when he died.   Is so, the betrothal would have manifested Galerius’ future dynastic intentions.  

Diocletian’s Motivation

For Lactantius (above), the fact that Galerius had emerged in so strong a position was enough to prove that Galerius had forced his will on a reluctant but incapacitated Diocletian.   However, there is another possibility: that this was the outcome that Diocletian himself desired:

1. ✴Constantius belonged to the same generation as Maximian.  Although his early death might not have been expected at this point, he was probably betraying signs of ageing.  His activities to date had been confined to his own territories of Gaul, Britain and Spain, and he had no direct experience of the operation of the central imperial administration, which had been centred on Diocletian’s court.
   

2. ✴Galerius, on the other hand,was perhaps ten years younger than Maximian and Constantius.  He had been Diocletian’s son-in-law and ‘righthand man’ for more than a decade.  He had defeated and humiliated the Persians in 298 AD, demonstrating both personal courage and audacity, and avenging the humiliations that the Persians had inflicted on the Romans over the previous forty years.   Diocletian probably regarded this victory and the treaty that resulted from it as the most important achievements of his reign.
   

Thus, Diocletian’s decision to accept Galerius’ nominees as the new Caesars might well have been the corollary to a more fundamental decision: that Galerius rather than Constantius should step into his shoes. 

This brings us to the attitude of Constantius, who was now, at least nominally, the senior Augustus to whom Severus would report.  Again, there is no evidence that he had any insurmountable objections to the new arrangement.  His attitude was perhaps well-summarised by Orosius:

1. “Constantius, ... who was of an extremely mild disposition, was satisfied with Gaul and Spain alone and permitted Galerius to take the other districts.  Galerius chose two Caesars:
   

2. -Maximinus, whom he stationed in the east; and
   

3. -Severus, to whom he entrusted Italy (‘Historiae adversum Paganos’ 7:25:15).
   

In other words, Constantius was apparently content to exercise power in Gaul (and in the associated regions of Britain and Spain), where he might reasonably expect to be untroubled by outside interference.  In return, he was content that Galerius and his nominated Caesars should run the rest of the Empire.

The evidence suggests that Diocletian had arrived at an entirely workable arrangement.  Thus, as Torben Christensen (referenced below, at p 119) observed:

1. “It is remarkable ... that the incontestable information on, for example, the appointment of consuls and the striking of coins contain no hint of a disagreement or conflict between the members of the [new] Imperial college. Everything indicates that the so-called second Tetrarchy, which lasted from Diocletian’s abdication on 1 May 305 to Constantius’ death on 25 July 306 [see below] worked entirely as intended”.
   

Reactions of Diocletian’s Colleagues

Lactantius’ imagined dialogue between Diocletian and Galerius in early 305 AD began with the selection of the new Caesars:

1. “It remained to choose Caesars by common consent:
   

2. “Galerius: ‘But,why ask the advice of Maximian and Constantius, since they will have to acquiesce in whatever we decide?’ 
   

3. Diocletian: ‘Certainly they will, for we must elect their sons’” (‘De Mortibus Persecutorum’, 18:8). 
   

Timothy Barnes (referenced below, 2011, at p 48) argued that this had been Diocletian’s intention since the creation of the Tetrarchy in 293 AD:

1. “If Diocletian were to die [or abdicate] and be replaced by .... Galerius, then Constantine, Constantius’ son would replace Galerius as the Caesar [in the east].  Similarly in the west, if  Maximian were to die [or abdicate], Constantius would automatically replace him ...., with Maxentius, Maximian’s son, as his Caesar”.
   

The respective dynastic claims of Constantine and Maxentius are discussed below.  For the moment, the discussion concentrates on how Maximian and Constantius might have viewed Diocletian’s actual decision, assuming (as argued above) that:

1. ✴Maximian had agreed (however reluctantly) to abdicate; and
   

2. ✴Constantius had accepted (perhaps less reluctantly?) that he would become senior Augustus in name only.
   

Maximinus in the East

Maximinus was probably younger and less experienced in military terms than Constantine, his putative competitor for the post of Caesar in the east.  However, Galerius’ decision to appoint him would not have surprised his colleagues:

1. ✴he was Galerius‘ closest male relative after Candidianus (who would subsequently be betrothed to his daughter); and
   

2. ✴Galerius, who had seen both Constantine and Maximinus in action, would understandably have concluded that Maximinus was the more loyal and less inclined to insubordination. 
   

Maximian and Constantius  would presumably have accepted that Galerius should be able, within reason, to choose his own Caesar (as Maximian, had probably done before him).  In any case, we cannot automatically assume that they would have preferred Constantine, as discussed below.  Assuming that they did not, then it is not difficult to see why Maximinus would have been an acceptable  to both of them.

Severus in the West

Their apparent acceptance of the choice of Severus in the west is more surprising.  Thus, Lactantius assumed that Maximian at least had been faced with a fait accompli.  Thus, during the discussion that he had imagined had taken place between Diocletian and Galerius on Severus’ appointment, he had Galerius announce that he had taken pre-emptive action:

1. “.... I have already despatched [Severus] to receive the purple from the hands of Maximian [in Milan]” (‘De Mortibus Persecutorum’, 18:12).
   

The implication was that neither Diocletian nor Maximian had had any choice in the matter. 

This theory is unlikely in the extreme, not least because Severus took over the territory that had previously been Maximian’s responsibility, and he therefore inherited what had been Maximian’s army.  Maximian could easily have blocked his appointment, had he wanted to, by subverting this army (as he was to do, to great effect, in 307 AD, as we shall see).  The reality was that Diocletian must have secured Maximian’s agreement to Severus’ appointment and to its corollary, that Galerius rather than Constantius take over de facto responsibility for peninsular Italy and Africa.

What then of the claim of Maxentius, who was not only as Maximian’s only son but also Galerius’ son-in-law?  His relative youth and complete lack of military experience (in stark contrast to the maturity and military experience of Severus) were obvious disadvantages.  In addition, he had a son whose excellent dynastic credentials might perversely have militated against Maxentius: both Maximian and Constantius might have seen the boy as a threat to the future interests of the three young sons of Constantius’ dynastic marriage to Maximian’s daughter (see below).  Finally, Lactantius’ claim that both Maximian and Galerius hated Maxentius, which might well have been true, cannot have helped.

This, of course is pure speculation.  The only certainty is that Severus did indeed become Caesar in the east, and that neither Maximian nor Constantius objected strongly enough to do anything about it.

Constantine

In the discussion above, Constantine has been the unacknowledged ‘elephant in the room’.  The virtue of this approach is that it provides at least a chance of being diverted by the fact that history is written by the victors, with the result that the most useful sources for the period probably over-emphasise his importance.  However, it is now time to include him in the discussion.

Early Life

According to the ‘Origo Constantini Imperatoris’: 

1. “[When] Constantius ... was appointed Caesar by Diocletian ..., he put away his former wife Helena and married Theodora, daughter of Maximianus ... But by his former wife, Helena, he already had a son Constantine ...” (1:2).
   

Unlike some other early sources, this one asserts that Constantius and Helena were formally married, a proposition supported in detail by Timothy Barnes (referenced below, 2011, at p 38).   The account continued:

1. “This Constantine, then, born of Helena, a mother of very common origin, [was] brought up in the town of Naissus [modern Niš, in Serbia] ...” (2:1).
   

He was probably originally named Flavius Constantinus, becoming Flavius Valerius Constantinus in 293 AD, when his father became Caesar Flavius Valerius Constantius.

We happen to know the date of Constantine’s birthday: the anniversary of the natales of (the by-then deified) divus Constantinus was recored in the entry under 27th February in the the so-called ‘Chronograph’ of 354 AD.  Unfortunately, the year in which he was born is not known.  The early sources (which, of course, might have shared a single original source) agree that he died when he was 66 years old, after a reign of 31 years (i.e. 306-37 AD).  For example, according to Eutropius:

1. “... [Constantine] died in the Villa Publica at Nicomedia, in the 31st year of his reign, and the 66th of his age” (‘Breviarium historiae Romanae’, 10:8:2).
   

This places his date of birth in ca. 270 AD.  However, modern scholars have published estimates that range across the following decade and at least one puts the date at 288 AD.  Timothy Barnes (referenced below, 2011, at p  3), who favoured the date 273 AD, argued that those scholars who favoured later dates had been misled by Constantine’s own propaganda.  For example, in his Letter Condemning Idolatry (ca. 324 AD), which Eusebius translated into Greek (‘Vita Constantini’, 2:51), Constantine claimed that he had been still been a youth when he had witnessed the events that led Diocletian to issue the first Edict of Persecution in Nicomedia in February 303 AD.  If the dating above is correct, Constantine would actually have been in his early thirties at this time!  Barnes’ explanation is compelling:

1. “Constantine ... deliberately lied [here] about his age for political reasons.... For, what could a mere boy have done to stop the persecution?”
   

The biography in the ‘Origo Constantini Imperatoris’ continued:

1. “[In the early part of his career, Constantine] was held as a hostage by Diocletian and Galerius, and did valiant service under those Emperors in Asia” (2.2).
   

The implication here might have been that the young Constantine was a hostage in the east for the continued loyalty of his father in Gaul.  However, this seems unlikely: there is no sign that Constantius’ loyalty was ever in doubt.  An alternative is that Constantine himself was recognised as a potential threat to the Tetrarchy: if so, he must have been unusually precocious.  It seems more likely that Constantine was being groomed at the courts of Diocletian and Galerius for future incorporation into the imperial college.  Eusebius’ account is thus more credible in tone:

1. “[Constantine] had been with his father's imperial colleagues [Diocletian and Galerius] and had passed his life among them ....  And even in the very earliest period of his youth, he was judged by them to be worthy of the highest honour.  An instance of this we have ourselves seen, when he passed through Palestine with [Diocletian], at whose right hand he stood, and commanded the admiration of all who beheld him by the indications he gave even then of royal greatness” (‘Vita Constantini’, 1:19).
   

Constantine certainly had a son by the time of the abdication.  Zosimus believed that this son was illegitimate:

1. “[In 317 AD], Constantine conferred the rank and title of Caesar on Crispus, his son by a concubine called Minervina, who was as yet but a youth” (‘Historia Nova’ 2:20:2).
   

However, in a panegyric (Panegyric VII, translated into English in Nixon and Rodgers, referenced below) that was delivered at Constantine’s court in 307 AD (on the occasion of his second marriage), the panegyrist claimed that Constantine had emulated his father by:

1. “... surrendering [himself] to the laws of matrimony immediately [his] boyhood was at an end ...” (4:1).
   

The translator (at note 10) regarded this as:

1. “... prima facie evidence that Constantine married in early manhood and that Minervina, the mother of Crispus, was not his concubine, as writers drawing on a hostile tradition [including Zosimus] allege .., but his lawful wife”.
   

Timothy Barnes (referenced below, 2011, at p 48) recorded that nothing is known about her, except that:

1. “... her name was Minervina, and ... she left [Constantine] a widower before 307 AD, after bearing him a son, Crispus, who was born no later than ca. 300 AD.”
   

There is some evidence to support the assertion (above) that Constantine had undertaken military service in ‘Asia’, if this can be taken as a general reference to the eastern part of the Empire.  In his ‘Oration to the Assembly of the Saints’, or at least in Eusebius’ Greek translation of it, Constantine wrote: 

1. “[The scriptures declare that] Memphis and Babylon shall be wasted and left desolate with their fathers' gods.  Now these things I speak ... having myself been present and seen [with my own eyes] the most wretched of these cities, the unfortunate Memphis” (16.2).
   

Timothy Barnes (referenced below, 2011, at p 51) translated the last phrase as ‘the pitiable fate of the cities”, which implies that Constantine had seen both Memphis and Babylon.  For his defence of this position, see Timothy Barnes (referenced below, 1982, at 41, note 59).  This might suggest that he had served with Diocletian in Egypt in 297-8 AD and with Galerius in his successful campaign against the Persians in 298 AD.  While possible, this is not conclusive:

1. ✴There is no direct evidence that Galerius penetrated as far as Babylon, some 40 miles south of the Persian capital of Ctesiphon, in 298 AD.
   

2. ✴Constantine might have accompanied Diocletian to Egypt in a documented trip in 301-2 AD, the probable occasion on which Eusebius (above) had seen the two men together in Palestine (en route to or from Antioch).  If so, he could have seen Memphis then.
   

There is, however, clear evidence for Constantius’ service under Galerius on the Danube: according to the ‘Origo Constantini Imperatoris’:

1. “After the abdication of Diocletian and [Maximian], Constantius asked Galerius to return his son; but Galerius first exposed him to many dangers.  For when Constantine, then a young man, was serving in the cavalry against the Sarmatians, he seized a fierce savage by the hair, carried off and threw him at the feet of [Galerius].  Then, sent by Galerius through a swamp, he entered it on his horse and made a way for [his comrades] to the Sarmatians, of whom he slew many, winning the victory for Galerius” (2:3).
   

As Péter Kovács (referenced below) pointed out, this dating must be wrong, because no Sarmatian campaigns are documented during the few months that Constantius spent with Galerius after the abdication (see below).  Kovács concluded:

1. “The campaign can [more probably] be identified with the Sarmatian war in 302 AD, when Galerius took the imperial title Sarmaticus for the third time”.
   

Timothy Barnes (referenced below, 2011, at p  180) dated this campaign to 302 or 304 AD.

Constantine might have spent the two years leading to the abdication at Diocletian’s court at Nicomedia:

1. ✴by his own testimony, he was in the city when the first Edict on the Persecution of Christians was issued in February 303 AD; and
   

2. ✴according to Lactantius (above), he was there again at the time of the abdication itself:
   

3. “[Constantine] was then at court, having long before been created by Diocletian a tribune of the first order”.
   

Constantine and the Appointment of Maximinus

Lactantius presented what seems to have been an eye-witness account of Diocletian’s last act as Augustus, when he announced his intention to abdicate and his decision on the appointment of the new Caesars: 

1. “... Diocletian and Galerius went in procession to publish the nomination of Caesars.  Every one looked at Constantine; for there was no doubt that the choice would fall on him.  The troops present, as well as the chief soldiers of the other legions, who had been summoned to the solemnity, fixed their eyes on Constantine, exulted in the hope of his approaching election, and occupied themselves in prayers for his prosperity.  Some three miles from Nicomedia, there is an eminence, on the summit of which [Galerius?  Diocletian himself?] had received the purple; and there a pillar, with the statue of Jupiter, was placed.  Thither the procession went.  An assembly of the soldiers was called. Diocletian, with tears, ... said that he had become infirm, that he needed repose after his fatigues, and that he would resign the Empire into more vigorous and able hands and, at the same time, appoint new Caesars.  The spectators, with the utmost earnestness, waited for the nomination.  Suddenly he declared that the Caesars were Severus and Maximinus.  The amazement was universal.  Constantine stood near in public view, and men began to question amongst themselves whether his name too had not been changed into Maximinus.  However, in the sight of all, Galerius ... put Constantine aside, drew [Maximinus] forward and, having divested [Maximinus] of the garb of a private person, set him in the most conspicuous place.  All men wondered who he could be and from whence he came; but none ventured to intervene or make objections, so confounded were their minds at the strange and unlooked-for event.  Diocletian took off his purple robe, put it on [Maximinus], and resumed his own original name of Diocles.  He descended from the tribunal, and passed through Nicomedia in a chariot; and then this old Emperor, like a veteran soldier freed from military service, was dismissed into his own country ...” (‘De Mortibus Persecutorum’, 19).
   

The general expectation that Constantine would be appointed is unsurprising: as noted above, he had a higher military rank than Maximinus and apparently enjoyed Diocletian’s favour.  Even if Galerius preferred to see his relative Maximinus appointed in the east, surely Constantine, the son of Constantius, the senior of the new Augusti, had a claim in the west.  Unfortunately, this dynastic claim was not without its complications. 

1. ✴Constantine’s mother Helena (whether or not she was formally married to Constantius) was an ‘outsider’, whom Constantius had put aside in order to marry Maximian’s daughter (or step-daughter) Theodora.
   

2. ✴Perhaps more importantly, Constantine himself had also married outside the charmed circle, and he already had one a young son, Crispus. 
   

Thus Diocletian and his colleagues might well have feared that the promotion of Constantine would have introduced a new dynastic line that could prejudiced the future prospects of the young sons of Constantius’ second, dynastic marriage to Maximian’s daughter.

Political Developments (306-8 AD)

Galerius’ period as Diocletian’s effective successor did not last long: he was not the man that Diocletian had been, and the edifice of power that Diocletian had so carefully constructed for him soon began to unravel:  

1. ✴Constantius caused him no obvious problems, but Galerius faced the first threat to his supremacy when Constantius died while on campaign in Britain in July 306 AD, as described in the page on Constantius as Augustus (305-6 AD).
   

2. ✴Constantine immediately claimed to be his father’s successor.  Galerius contained this threat by persuading him to accept the rank of Caesar, subordinate in principal to Severus, whom he promoted to be the new Augustus, as described in the page on the Accession of Constantine (306 AD).  
   

3. ✴Maxentius seized power in Rome shortly after Constantine’s elevation to the imperial college.  Galerius refused him recognition, but Maximian returned from retirement to Rome in order to support his son.  Galerius sent Severus against them in the late summer, and both Maximian and Maxentius took the rank of Augustus during the campaign (Maximian, of course, for the second time).  Severus was defeated, captured and forced to abdicate, as described in the page on Maxentius and Maximian in Rome (306-7 AD).
   

4. ✴Maximian and Maxentius forged an overt alliance with Constantine after the defeat of Severus.   Maximian travelled to Constantine’s court, where he elevated him to the rank of Augustus and gave him the hand in marriage of his daughter, Fausta.  Maxentius and Constantine now formed part of Maximian’s Herculean Dynasty (306-7 AD), which had been formed to deter Galerius from invading Italy and avenging the defeat of Severus.  This page then describes how it began to unravel:
   

5. •Galerius undermined it by invading Italy in September 307 AD, while Maximian was still in Trier.  Maxentius executed the imprisoned Severus and refused to leave the safety of Rome to engage Galerius in battle.  As winter advanced, Galerius was forced to withdraw.
   

6. •When Maximian returned to Rome, his relations with the newly prestigious Maxentius deteriorated.  Matters came to a head in April 308 AD, when Maximian attempted to seize power but failed to persuade the army to support him.  He fled to Constantine’s court, where he lived as an honoured guest, but his short period as the head of a revived Herculean dynasty was at an end.
   

Galerius, who returned to Serdica with his prestige in tatters in late 307 AD, now began the slow business of rebuilding the imperial college and reasserting his pre-eminent position within it.  This last phase of his career is described in the page Galerius II (308-11 AD).