Diocletian\'s Tetrarchy & the Dynastic Principle

[Theodosius the Great]

Avete Omnes,

I'd like to ask about the Tetrarchy as it was originally conceived by Diocletian. Reading a biography of Constantine the Great I came across the fact that Constantine was betrothed to Maximian's daughter, Fausta, in 293 A.D.. (Fourteen years later the two were married.)

This seems strange to me given that the Tetrarchy was supposedly designed not to foster traditional dynasties. It was a merit based system as opposed to a hereditary one. So, then, why was Constantine, the son of a legitimate emperor, betrothed to a daughter of another legitimate emperor in the first place ? Clearly this 14 year engagement between the two imperial offspring had undermined the merit-based system Diocletian had supposedly envisioned. Constantine had all the semblance of being an heir-apparent.

True, the marriage didn't occur for over a decade but, AFAIK, the engagement remained in effect. How do we account for this built-in design flaw ? How could the army or anyone else not anticipate that Constantine would one day become emperor ?

Could it be that maybe Diocletian did not in fact conceive of a clear-cut Tetrarchy based solely on merit ? In other words, was the idea of the Tetrarchy constantly evolving in Diocletian's mind ? What do you think ?

~Theo

[Robert Vermaat]

Constantine had all the semblance of being an heir-apparent.

The semblance, but yet he wasn't considered as such. Constantine effectively was a usurper when his father died, and his claim for the throne had to be enforced by the troops. So effectively the system worked, but Constantine broke it. After that, the Tetrarchy was dead, because after Constantine's death it was the military that did not accept anyone but the sons of Constantine. In the days and weeks after his death they killed a large number of family. I doubt that this was what he would have wanted, btw...

True, the marriage didn't occur for over a decade but, AFAIK, the engagement remained in effect. How do we account for this built-in design flaw ? How could the army or anyone else not anticipate that Constantine would one day become emperor ?

Well, that's the point, it wasn't an built-in design flaw at all. Diocletian may not have foreseen the effect that this arrangement, (no doubt wrought to strengthen the ties between the men in power) could have been seen as a promise of things to come by both Constantine and the army. But it flies in the face of the system behind the Tetrarchy itself.

Could it be that maybe Diocletian did not in fact conceive of a clear-cut Tetrarchy based solely on merit ? In other words, was the idea of the Tetrarchy constantly evolving in Diocletian's mind ? What do you think ?

I doubt that Diocletian failed to believe in his own system. But I do think that he greatly underestimated some of the powers at work. I mean, any historian of the time could have told him about the power of the armed forces, and the need to get these powers to agree.
The military may have been anxious about the 'merit' system.
On the one hand this system seems to be in their favour, as 'good' men may not make 'bad' wars (the army had no reason to think well about the past 60 years).
But on the other hand they will have felt (as we see would happen) that some ambitious men might not agree about the 'merit' of a candidate, and go for the job themselves. Which is exactly what happened with Constantine. As a result, the army chose the 'stability' of a dynasty, which was something no-one could argue about.

Of course, that did stabilise the (ever-present) problem of succession (I consider it one of the main problems of the Roman Empire) for some time. But in the end the succession of mere babies again paved the way for ‘strong men’ to become the power behind the throne, and the resulting power struggle that resulted to me is one of the major causes for the fall of the West.

[Theodosius the Great]

Constantine had all the semblance of being an heir-apparent.

The semblance, but yet he wasn't considered as such.

Ah, but "wasn't considered as such" by whom ? Diocletian and his colleges ? The Senate ? The army ? The latter, I think, may have seen Constantine as heir-apparent since the army may not have been privy to Diocletian's succession scheme. If true, then what were they to think when they saw Constantine fight beside his father ?

(One may counter this question with another : how would they know about his engagement to Maximian's daughter ? I would answer by saying it would be difficult for the most common soldier not to have known after a 14-year state of arrangement. )

Diocletian may not have foreseen the effect that this arrangement...it flies in the face of the system behind the Tetrarchy itself

So it may be simple short-sightedness on his part ? Possibly, but Diocletian was an extraordinary planner. The arrangement did solidify the alliance, as you said, between Constantius and Maximian but at the expense of undermining the system, it would seem. So, it may have been politically expedient and necessary in the short term but damaging in the long run ? This seems like the best answer so far, IMO.

I doubt that Diocletian failed to believe in his own system. But I do think that he greatly underestimated some of the powers at work.

Yes, given the marriage arrangements vis-a-vis his dynastic arrangements Diocletian seems to have been overly optimistic about the future. Perphaps he thought his earned prestige would be enough for the system to carry on after his abdication ?

By the way, there's a touch of irony about Diocletian creating a merit-based succession principle. He himself was defeated by a rival in battle but the victor was killed during the fighting leaving only Diocletian to become emperor. He was not a gifted commander.

~Theo

[Robert Vermaat]

Constantine had all the semblance of being an heir-apparent.

The semblance, but yet he wasn't considered as such.

Ah, but "wasn't considered as such" by whom ? Diocletian and his colleges ? The Senate ? The army ? The latter, I think, may have seen Constantine as heir-apparent since the army may not have been privy to Diocletian's succession scheme. If true, then what were they to think when they saw Constantine fight beside his father ?

Didn't I say just that?

Indeed, the army got the idea. But then the army was not a part of the Tetrarchy, weren't they? Constantine was not legally considered to be the heir of Constantius. The father did not proclaim his son to be his successor, but the army did (no doubt 'guided' by the officers in Constantius' staff, that's usually how such things work). For all other parties, Constantine was legally a usurper. And if things had gone differently he would have been described in our history books in similar terms as Magnentius and Magnus Maximus. yet another British-based tyrant. But he won and that was that. :wink:

(One may counter this question with another : how would they know about his engagement to Maximian's daughter ? I would answer by saying it would be difficult for the most common soldier not to have known after a 14-year state of arrangement. )

Such things were public knowledge. Powerful men of course can't keep the bethrothal of their children a secret. But then, i don't believe that common soldiers make history, they're usually 'guided'.

Diocletian may not have foreseen the effect that this arrangement...it flies in the face of the system behind the Tetrarchy itself

So it may be simple short-sightedness on his part ?

I think that Diocletian seriously underestimated the 'free will' of the army, yes.

I doubt that Diocletian failed to believe in his own system. But I do think that he greatly underestimated some of the powers at work.

Yes, given the marriage arrangements vis-a-vis his dynastic arrangements Diocletian seems to have been overly optimistic about the future. Perphaps he thought his earned prestige would be enough for the system to carry on after his abdication ?

If so, that too would could be seen as short-sighted.

[Theodosius the Great]

The father did not proclaim his son to be his successor, but the army did (no doubt 'guided' by the officers in Constantius' staff, that's usually how such things work).

Yes, the army at their officers' prompting and that of an allied Frankish 'king' now that I recall the event.

For all other parties, Constantine was legally a usurper. And if things had gone differently he would have been described in our history books in similar terms as Magnentius and Magnus Maximus. yet another British-based tyrant. But he won and that was that. ;-) )

Agreed. Though Constantine seems to be among the few usurpers to obtain legal recognition from his rivals when Galerius legitimized him (though he demoted Constantine to 'Caesar' in order to save face as much as he could, IMO). A bloodless rebellion - surely a novelty, especially in a Roman context

Powerful men of course can't keep the bethrothal of their children a secret. But then, i don't believe that common soldiers make history, they're usually 'guided'.

Agreed with everything. Good point about the officers. It's consistent with my readings about other civil wars, (particularly, the Year of the Four Emperors). At worst, soldiers tend to "mutiny" (analogous to a modern "strike" in the workplace) until they get what they want. Revolts tend to be fostered by the higher-ups.

Thanks for the input, Robert.
I never did like the idea of the Tetrarchy but it now seems even more ill-founded given the rivalries that were allowed to foster under Diocletian. Picking two fellow colleges with sons was a bad choice, IMO. He sowed the seeds of the Tetrarchy's destruction it would seem.

~Theo

[S SEVERUS]

I never did like the idea of the Tetrarchy but it now seems even more ill-founded given the rivalries that were allowed to foster under Diocletian. Picking two fellow colleges with sons was a bad choice, IMO. He sowed the seeds of the Tetrarchy's destruction it would seem.

~Theo

I think Diocletian picked Maximian for the fact that his collegue accepted to be his minor and was a good general (if Macimian is one of the two you are referring to)

Question : in what battle did Diocletian loose from a rival? I can't remember that.

[Theodosius the Great]

Yes, Maximian was one of the two colleagues with sons. As his later actions proved he was by far the most treacherous of the original four tetrarchs. Though he was a competent general - defeating the Moors, Germanic tribes, and rebellious 'British' troops. But Diocletian misjudged his character.

Question : in what battle did Diocletian loose from a rival? I can't remember that.

At the Battle of the Margus it seems he won by default after Carinus failed to press his advantage when Diocletian's ranks broke. Carinus may have already been asassinated at that critical point, according to author Stephen Williams. (If true, this is reminiscent of Aetius vs. Bonifacius in the 5th century.)

~Theo

[Robert Vermaat]

I never did like the idea of the Tetrarchy but it now seems even more ill-founded given the rivalries that were allowed to foster under Diocletian. Picking two fellow colleges with sons was a bad choice, IMO. He sowed the seeds of the Tetrarchy's destruction it would seem.

Well, I like to think that idea was in itself good. But it was not right for the times. In itself though, it recognised the impossibility of effective Roman rule from one geographical spot. It seems Diocletian and a lot of others really thought it could work.

The succession was always one of the major Roman weak spots. Whatever you do, army or dynasty, there's always violence involved if any of those not included in the succession get the idea that they can get the throne. By itself a dynasty is more secure than a tetrarchy, but only if the successors are adults (preventing the possibility of guardians. If those outside the dynasty are not able to get the throne they might not go for it.

[Theodosius the Great]

@Vortigern

If I may, let me elaborate on what I said.

Power-sharing, IMO, never works either in familial dynasties (at least between brothers) or otherwise. Clearly it has a bad track record with fraternal dynasties, e.g. : the Severan, Constantinian, and Theodosian. The one exception I can recall is the Valentinian dynasty.

Non-fraternal power-sharing has a worse although shorter record, e.g. : the Triumvirate and the Tetrarchy. I don't include Marcus Aurelius and Lucius Verus because, although they were both 'Augusti', the empire was still one entity. Also, I do not mention Gratian appointing Theodosius his eastern colleague since that arrangement was fairly ad hoc under unique circumstances.

Well, I like to think that idea was in itself good. But it was not right for the times.

Two reasons I dislike the Tetrarchy are : a) it didn't work / last, and b) it would, I predict, cause the four regions to drift apart culturally, the empire would lose cohesion. Eventually, as we saw under Theodosius' sons, the two halves would only look after their own realms at the expense of the other if necessary (as they would see it). Power-sharing intrinsically promotes regionalism or separatism, IMO. Where there was one strong empire, there would be two (or four) weaker ones.

In itself though, it recognised the impossibility of effective Roman rule from one geographical spot.

I keep reading this assessment in different places, including RAT, but I can't remember the rationale behind it. Did not Constantine disprove it ? He ruled a good decade very comfortably as sole 'Augustus'. And like the first Augustus, he appointed his male relatives to military posts on troubled parts of the frontier. But unlike Augustus, he appointed them all as 'Caesars' and alloted them their own territories. Big mistake, IMO.

Ideally, I think there should only be one 'Augustus' at any one time and one, undivided, empire with maybe one 'Caesar' as heir-apparent, preferably a natural son. If there are many sons then they may be useful surrogates for military campaigns but should not expect to inherit the throne unless the 'Caesar' dies unexpectedly. That way you don't encounter many of the problems associated with boy-emperors since there is only one empire.

It seems Diocletian and a lot of others really thought it could work.

The Tetrarchy was not all that novel an idea, as Diocletian should have known about the Triumvirate. Octavian and Antonius were bound with a familial marriage alliance yet ultimately they turned against each other. Then again, Diocletian had little or no formal education - possibly being an ex-slave, IIRC.

By itself a dynasty is more secure than a tetrarchy, but only if the successors are adults (preventing the possibility of guardians. If those outside the dynasty are not able to get the throne they might not go for it.

In a Late Roman context, I'm not sure I understand your assessment. I mean, the only model we have to observe in this time period is the Theodosian. It didn't become extinct from external sources. By the time the empire became more thoroughly Christian, dynasties seem to thrive much more easily even into Byzantine times. So, did you mean 'dynasty' or 'empire' in your statement ?

~Theo

[SMC]

I think we need to ask how much the tetrarchy was really envisaged as a long term solution by those involved.
Diocletian took power by force and then appointed a co-emperor some time afterwards. They each associated themselves with Romes most powerful deities. There was no indication of this being anything more than two men ruling, one subordinate to the other. The addition of caesars was a later step and caused problems from early on.
I'm hazy on dates and don't have books to hand but I think Corcoran's book goes in to a lot of detail on this.

[Lupianus]

Funny enough, I once wrote a thesis in university about the legality of Constantine's succession.
First, I'm a strong supporter of the theory, that at least Diocletian had a plan of how to organise a tetrarchy. There are many historians who are not so certain about that - still a matter of debate here in Germany.

Taking a planned system into account, I found no contemporary account of Constantine's acclamation for Augustus. All he did was accompanying his commander (coincidentally his natural father) and being introduced to the army as his legal successor. He was acclaimed as imperator, but that's not the same. Constantius may even have appointed Constantine himself, before he died - at least, he had the right to do it, since he was senior Augustus (like Diocletian before).
Furthermore, I wouldn't overemphasize Constantius being Constantine's natural father. As far as we know, Helena wasn't Constantius' official spouse - hence the relationship between father and son was most probably a professional one. Perhaps Constantius deliberately chose his natural son as the next Caesar, since Constantine showed needed qualities - after all, he prevailed as emperor against great odds, didn't he.

Initially, Constantine accepted being officially called Caesar (inscriptions and the like), whereas real problems only arose as Severus failed to depose the usurper Maxentius and the other emperors ignored Constantine's (legal) claim for moving up into the position of Augustus.

That there were still 'tetrarchic thoughts' around after Constantine's rise to single emperor might show the incidents of 326: Constantine murdered his wife Fausta (daughter of Maximian) and Crispus (Constantine's first Caesar). Interestingly, it's the 20th year of Constantine's reign, so Crispus could have asked for a change in command, supported by one of the last eyewitnesses of the old tetrarchy, Fausta. Pity for them, after struggling for power very hard, Constantine wasn't in the mood for such thoughts anymore...

[Robert Vermaat]

Interesting thoughts Til!