WI Valentinian I Lives Longer

PoD in 375.
What if instead of dying of a blood clot he dies [later]? How does the empire change with the last strong emperor of the west ruling for an extra 20 years? Can he reform the empire to not make it collapse in the west? Can he save his brother from doom at Adrianople? Can he make his sons competent?
[T]his question needs to get a real discussion thread. I mean seriously, I know he was technically "only" the Western Roman Emperor, but he was unambiguously the senior of his brother while they both reigned, meaning that, with the exception of a very brief window of time towards the end of Theodosius' reign, this was the last time the Empire was effectively unified. And considering just how much started going wrong almost immediately after his death, you would think this site would be more curious as to what would have changed had he still been alive.
Personally, I’d also be fine just extending his life just to 389 or so, giving him the same lifespan as Constantine; his sons are both still adult by then, so it works as well, I think.

-----CONSOLIDATE-----

One of the interesting things to think about in this scenario -- when comparing the reigns of Valentinian and Valens to those of Gratian and Theodosius, one of the most notable changes that stand out is imperial policy toward paganism. Ammianus Marcellinus, a contemporary pagan writer, said of Valentinian was "distinguished for religious tolerance... He took a neutral position between opposing faiths, and never troubled anyone by ordering him to adopt this or that mode of worship ... [he] left the various cults undisturbed as he found them", and that Valens was much the same. By contrast, Gratian, aside from famously removing the Altar of Victory, had begun a state policy of confiscating the wealth of pagan priests, temples, and vestal virgins; Theodosius, of course, is infamous for the destruction and conversion of pagan temples across his reign, for his suppression of pagan rituals (far, far surpassing existing bans on animal sacrifices and the like), and essentially dismantling the vestiges of non-orthodox-christian religion as far as his effective authority would allow.

If Valentinian lives longer, and he is somehow able to prevent the Catastrophe of Adrianople -- and yes, that is another important question to consider here -- but if we can imagine both brothers living into their sixties, we would, at minimum, be pushing back this religious development; it's very likely that Ambrose of Milan doesn't achieve nearly the same level of political influence in the empire as he got OTL. And if Gratian predeceases his father (such that Valentinian II is the new heir), that greatly reduces the chances that the next generation of emperors dismantling this level of religious tolerance either.

What do you guys think?
 
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One of the interesting things to think about in this scenario -- when comparing the reigns of Valentinian and Valens to those of Gratian and Theodosius, one of the most notable changes that stand out is imperial policy toward paganism. Ammianus Marcellinus, a contemporary pagan writer, said of Valentinian was "distinguished for religious tolerance... He took a neutral position between opposing faiths, and never troubled anyone by ordering him to adopt this or that mode of worship ... [he] left the various cults undisturbed as he found them", and that Valens was much the same. By contrast, Gratian, aside from famously removing the Altar of Victory, had begun a state policy of confiscating the wealth of pagan priests, temples, and vestal virgins; Theodosius, of course, is infamous for the destruction and conversion of pagan temples across his reign, for his suppression of pagan rituals (far, far surpassing existing bans on animal sacrifices and the like), and essentially dismantling the vestiges of non-orthodox-christian religion as far as his effective authority would allow.
TBH I always got the impression that Theodosius' anti-pagan edicts weren't really that well enforced -- it was more a statement of "Yep, the Empire is definitely Christian" than a serious attempt to root out paganism. Meanwhile the Altar of Victory affair was more symbolic than anything else. So I don't think it will make much of a difference in the long run -- Christianity was on the up anyway during this period, making it highly likely that you'd get some sort of suppression of pagan cults anyway, and whether it happens in the late fourth or early fifth century probably doesn't have that many effects.

IMHO, the more interesting change would be against the Goths. Valentinian and Valens seem to have had a good working relationship, unlike Valens and Gratian, so ITTL it's quite likely that Valentinian will send Western reinforcements to help Valens sooner, quite possibly resulting in a Roman victory. This in turn puts the Empire in a better position to weather the barbarian invasions of the early 400s -- the Goths were a big destabilising factor in both East and West, so without them the Emperor has more attention and resources to turn towards the frontiers.
 
If you are interested, I share a link, unfortunately in Italian, on a timeline that starts from this Point of Divergence


Unfortunately, not knowing the author, I am unable to ask permission to translate it into English :oops: 😞
 
IMHO, the more interesting change would be against the Goths. Valentinian and Valens seem to have had a good working relationship, unlike Valens and Gratian, so ITTL it's quite likely that Valentinian will send Western reinforcements to help Valens sooner, quite possibly resulting in a Roman victory. This in turn puts the Empire in a better position to weather the barbarian invasions of the early 400s -- the Goths were a big destabilising factor in both East and West, so without them the Emperor has more attention and resources to turn towards the frontiers.
I had been a little hesitant to address the massive implication that is Adrianople -- even averting the disaster it absolutely would be a game changer in Roman history. But that hesitation likely isn't warranted -- as you say, Valentinian had a better relationship to his eastern counterpart than Gratian did, and he absolutely would be sending aid to his brother. And the TL @AndreaConti provided (much thanks, btw!) does a good job showing how the battle could have played out differently with that change.

So this should prove a fascinating scenario to consider.
 
I had been a little hesitant to address the massive implication that is Adrianople -- even averting the disaster it absolutely would be a game changer in Roman history. But that hesitation likely isn't warranted -- as you say, Valentinian had a better relationship to his eastern counterpart than Gratian did, and he absolutely would be sending aid to his brother. And the TL @AndreaConti provided (much thanks, btw!) does a good job showing how the battle could have played out differently with that change.

So this should prove a fascinating scenario to consider.


actually about the whole thing about the political chaos that then led to the Battle of Adrianople Otl, I think it can be mitigated if Valentinian survives, because he could take over the management of the entire hastily created reception apparatus on the Danube without them having to inform the emperor Valens who is preparing for war against Persia, wasting a lot of time and worsening the conditions in which the Goths found themselves ( given that with his older brother much closer to him, Valens could delegate to him the question of how to welcome them into the empire, because we must remember that Otl the Goths spent two years on the border, without the supplies suitable to feed 200 thousand people, suffering abuse from the local "administrators" and with the Hun threat always present in their minds, after all they only wanted two things, basically : to be welcomed into the empire as citizens (they had also calmly accepted to serve in the army, it was quite normal for them ) and to be able to save themselves from the Hunnic repercussions against them ( because they had not wanted to submit to their domain )

furthermore it had now become a recurring practice for the empire to welcome immigrants from the barbaricum, to then use them in the army, or employed as workforce or to settle in areas where diseases and famines had previously reduced the population, all this had already been done since at least Marcus Aurelius, and also very successfully ( it had become one of the empire's strong points, that of integrating the populations close to it, and also happened that when there were no populations bordering the empire pushing to enter, it was the emperor himself who ordered an expedition to force people from outside to enter ) considering the numerous campaigns he led in Gaul against the Germanic populations, I see him establishing a part of the refugees in the province to try to repopulate it in a small part ( given the numerous raids and wars that saw it involved from 350 until around 368 )
 
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What do you guys think of the the position that the (OTL) Battle of Adrianople effectively crippled the ability of (either) Roman Empire to field an army of significant size for decades thereafter? If you do agree, how do you think that changes Roman history?

One, possibly less pleasant, effect of this, is that the East is more willing to wage war on the Sassanids. I say “possibly less pleasant”, because one debatable effect of Rome’s precarious situation OTL was that the eastern border of Rome was more or less stable for 140 years after Julian’s invasion; that more-or-less stability ended in the 6th Century, and flipped into a century of near perpetual war (526 to 628). Maybe this unduly pessimistic of me, but I can’t shake the feeling that Eastern Rome having more troops just means that perpetual war period gets started sooner; that's probably a fatalistic assumption, but Valens was getting ready for another campaign against Persia, wasn't he?

Anyway, reading more of the TL linked by @AndreaConti (I'm up to 383), I did have some thoughts: was Valerio Petronio based on an OTL figure? Also, the TL nods to OTL events in ways that seem out of character for the TL itself -- for example, Magnus Maximus still starts his rebellion in 383, even though he (obviously) gets crushed just a few months in; also, Ambrose removes the Altar of Vicrory from the Senate while Valentinian and Gratian are out campaigning, which is frankly an astounding level of chutzpah. Though on the subject of Magnus Maximus -- would you guys say preventing his rebellion (or seriously curtailing it) would have major implications for the history of Britain down the line?

Thanks.
 
What do you guys think of the the position that the (OTL) Battle of Adrianople effectively crippled the ability of (either) Roman Empire to field an army of significant size for decades thereafter? If you do agree, how do you think that changes Roman history?

One, possibly less pleasant, effect of this, is that the East is more willing to wage war on the Sassanids. I say “possibly less pleasant”, because one debatable effect of Rome’s precarious situation OTL was that the eastern border of Rome was more or less stable for 140 years after Julian’s invasion; that more-or-less stability ended in the 6th Century, and flipped into a century of near perpetual war (526 to 628). Maybe this unduly pessimistic of me, but I can’t shake the feeling that Eastern Rome having more troops just means that perpetual war period gets started sooner; that's probably a fatalistic assumption, but Valens was getting ready for another campaign against Persia, wasn't he?

Anyway, reading more of the TL linked by @AndreaConti (I'm up to 383), I did have some thoughts: was Valerio Petronio based on an OTL figure? Also, the TL nods to OTL events in ways that seem out of character for the TL itself -- for example, Magnus Maximus still starts his rebellion in 383, even though he (obviously) gets crushed just a few months in; also, Ambrose removes the Altar of Vicrory from the Senate while Valentinian and Gratian are out campaigning, which is frankly an astounding level of chutzpah. Though on the subject of Magnus Maximus -- would you guys say preventing his rebellion (or seriously curtailing it) would have major implications for the history of Britain down the line?

Thanks.



well, as you certainly pointed out, more troops in the East makes it rather probable that the hostilities between the Sassanids and the Romans would worsen (unfortunately) and Valens was actually preparing the army to march against Persia, but I would say that the battle of Adrianople most crushed the war capabilities of the east rather than west of the empire in the short term ( it was the eastern troops who lost 2/3 of their most military-experienced personnel, who would have been very useful against the Hun incursions and their auxiliaries who were about to start seriously in this period ) I believe instead that what broke the Western strength were the numerous usurpations following the death of Valentinian first and that of Theodosius then ( in particular his death after the very tiring military campaign of 394 was truly a serious crisis, because Honorius was a child , Stilicho was surrounded by enemies and you have to face at least many usurpers in the space of a few years, with the few resources at his disposal, without considering the unresolved question of the Goths ) finally I believe that an emperor more focused on not having to run from one part of his dominions to another to resolve one crisis after another, could give the right attention to the provinces of Britain and northern Gaul, which were suffering continuous and massive incursions Saxons in Otl ( which increased the revolts of the troops stationed there, which elevated the first general capable of stopping one of these raids successfully )
 
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TBH I always got the impression that Theodosius' anti-pagan edicts weren't really that well enforced -- it was more a statement of "Yep, the Empire is definitely Christian" than a serious attempt to root out paganism. Meanwhile the Altar of Victory affair was more symbolic than anything else.

Correct, the whole edict was more aimed at the already Christian population and the general aim was to tell them to stop being heretics and join the official Nicene creed. The fact that Arcadius, Honorius and Theodosius had to decree again and again that individual temples to be converted into churches (usually abandoned ones) is more a proof of the fact that very few people in the empire at the time (in position of power) were actively trying to enforce some official mandate to dismantle the old cults and their temples (or else you would not have any temple in the V century to begin with).

So I don't think it will make much of a difference in the long run -- Christianity was on the up anyway during this period, making it highly likely that you'd get some sort of suppression of pagan cults anyway, and whether it happens in the late fourth or early fifth century probably doesn't have that many effects.

Most likely yes. Valentinian had a quite hand-off approach to religion but unless the empire gets an emperor sympathetic to pagan cults (or equally apathetic to both creeds), people in the empire are gonna see how advantageous it is to be a Christian (with the uneducated massed probably moving first to a syncretic version of Christianity).

IMHO, the more interesting change would be against the Goths. Valentinian and Valens seem to have had a good working relationship, unlike Valens and Gratian, so ITTL it's quite likely that Valentinian will send Western reinforcements to help Valens sooner, quite possibly resulting in a Roman victory. This in turn puts the Empire in a better position to weather the barbarian invasions of the early 400s -- the Goths were a big destabilising factor in both East and West, so without them the Emperor has more attention and resources to turn towards the frontiers.

And even assuming Adrianoples still happens (what are the odds of that battle still taking place in this timeline?), it is extremely unlikely that the events that led to the Goths becoming a Western problem (when originally they were an Eastern one) would still be here for them to exploit.

What do you guys think of the the position that the (OTL) Battle of Adrianople effectively crippled the ability of (either) Roman Empire to field an army of significant size for decades thereafter? If you do agree, how do you think that changes Roman history?

No, it did not. The following civil wars and the Gothic mutiny of 408 did that.

One, possibly less pleasant, effect of this, is that the East is more willing to wage war on the Sassanids. I say “possibly less pleasant”, because one debatable effect of Rome’s precarious situation OTL was that the eastern border of Rome was more or less stable for 140 years after Julian’s invasion; that more-or-less stability ended in the 6th Century, and flipped into a century of near perpetual war (526 to 628). Maybe this unduly pessimistic of me, but I can’t shake the feeling that Eastern Rome having more troops just means that perpetual war period gets started sooner; that's probably a fatalistic assumption, but Valens was getting ready for another campaign against Persia, wasn't he?

Persia was dealing with its own problems in the East (Turks I think) plus an Armenian rebellion in the V century. The Romans did not join the party (also thanks to Theodosius II being a protege of the Persian king). Conflicts only resumed when the issue of the shared defense (or expenses for said defense) in the Caucasus emerged, with the Romans refusing to pay for that. Otherwise the Romans were more or less happy with the status quo following the last Roman-Persian war of the IV century.
 
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Not really, Valens, especially after he became senior emperor, tried to revive the Arian cause, creating instability across the East by exiling orthodox bishops like Athanasius of Alexandria.
Looking specifically into it, and it does seem that Valens' relationship to Arianism, and subsequently to Nicene Christianity, is a matter of some recent historical contention. Some googling brought me this article, which seems to get to the heart of the matter:
Maijastin Kahlos said:
Several Christian writers such as Ambrose of Milan demanded that emperors support what they regarded as the true religion and the true version of Christianity. Christian emperors should not allow religious dissent. An emperor’s moderate attitude to religious dissenters could be twisted into negligence or laxity. If the emperor showed too much forbearance towards non-Christians, Jews, or heterodox Christians, he could be labelled as a ‘pagan’, ‘paganizing’, a Jew, ‘Judaizing’, an apostate, or a ‘heretic’ himself. Theodoret paints Valens as a friend of pagans: Valens gave “complete license” to everyone – “those under cover of Christian name, pagans, Jews, and the rest” – to worship in any manner they wished. The only exception were the Nicenes: thus, the emperor was “a foe to none but them who held the apostolic doctrine”, driving them from their churches. As a consequence, as Theodoret states, pagan and Jewish practices flourished in Antioch under Valens’ reign. Moreover, all this was public: “The rites of Jews, of Dionysus, and of Demeter were now no longer performed in a corner, as they would be in a pious reign, but by revelers running wild in the forum.” Valens’ befriending of pagans is contrasted with Theodosius I who makes an end to all this wickedness.
Now, there may be a case that Valens did not do as well as his brother at enforcing "disciplined toleration" within his sphere of the empire -- that's a discussion worth having -- but I think we can all agree that there probably wasn't a "persecution" of Nicene Christianity in the east around this time?

Moreover, two things stand out to me about the accounts of religious "disorder" during Valens' reign -- the first is that the issues only really started to escalate after the death of Athanasius of Alexandria, which itself was only a year and a half earlier than Valentinian's; and second, that much of the polemics against him written after his death utilize the historical fact of his devastation at Adrianople to be a clear sign of God's divine displeasure of his religious policies. Since we're talking about an alternate TL where said brother lives longer and said devastation is averted, it very may well be pretty reasonable to speculate that the reception of Valens policies toward Arianism, Nicene Christianity, and non-Christian citizens will be quite different from OTL.

Does this make sense?

EDIT ADD: One more quote from the article:
Was Valens ‘Arian’, as the hostile sources state? It is possible that in Valens’ case, the simple labels of ‘Arian’ and ‘Nicene’ are not functional. We might even ask whether he was keenly involved in doctrinal issues. The emperor probably supported the Homoian communities because they were dominant in most regions in the East as he attained the throne; he may have simply wanted to maintain the status quo for the practical reasons of social tranquility. The methods the emperor used for keeping order in the Roman Empire were the traditional ones and they were not nice ones – confiscations and banishments. For the Nicene church leaders under pressure, they were persecution, and in their interpretation, they were due to doctrinal issues.
 
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Looking specifically into it, and it does seem that Valens' relationship to Arianism, and subsequently to Nicene Christianity, is a matter of some recent historical contention. Some googling brought me this article, which seems to get to the heart of the matter:

Now, there may be a case that Valens did not do as well as his brother at enforcing "disciplined toleration" within his sphere of the empire -- that's a discussion worth having -- but I think we can all agree that there probably wasn't a "persecution" of Nicene Christianity in the east around this time?

Moreover, two things stand out to me about the accounts of religious "disorder" during Valens' reign -- the first is that the issues only really started to escalate after the death of Athanasius of Alexandria, which itself was only a year and a half earlier than Valentinian's; and second, that much of the polemics against him written after his death utilize the historical fact of his devastation at Adrianople to be a clear sign of God's divine displeasure of his religious policies. Since we're talking about an alternate TL where said brother lives longer and said devastation is averted, it very may well be pretty reasonable to speculate that the reception of Valens policies toward Arianism, Nicene Christianity, and non-Christian citizens will be quite different from OTL.

Does this make sense?

EDIT ADD: One more quote from the article:


however we know from Ammianus Marcellinus, that Valentinian, making use of the help of Pope Damasus I ( pontiff who had the topic very close to his heart given that his election followed a series of very serious divisions in the Roman clergy itself and with the election of a first anti-pope named Ursinus ), adopted an uncommon policy of religious tolerance in 371 , which according to Ammianus " where no one should be bothered with orders to adopt this or that cult " although the emperor himself was a fervent supporter of Nicene Christianity, even if he was not always able to respect this tolerance first and foremost, as when in 375 he promulgated edicts against the Donatists, guilty of having supported Firmus, or when he condemned in 367 to death 4 Milanese Christians guilty of having offended him
 
Now, there may be a case that Valens did not do as well as his brother at enforcing "disciplined toleration" within his sphere of the empire -- that's a discussion worth having -- but I think we can all agree that there probably wasn't a "persecution" of Nicene Christianity in the east around this time?
I don't see why we should agree that. The primary sources say there was, and I'm not aware of any evidence directly contradicting them. ISTM that scholarly doubts are based mostly on a combination of (1) a general "hermeneutic of suspicion" towards sources (everyone's assumed to be manipulating the facts to push an agenda), and (2) organised religion in general, and Christianity in particular, being low-status in academic circles, meaning that ecclesiastical authors suffer even more from (1) than secular.
 
I don't see why we should agree that. The primary sources say there was, and I'm not aware of any evidence directly contradicting them. ISTM that scholarly doubts are based mostly on a combination of (1) a general "hermeneutic of suspicion" towards sources (everyone's assumed to be manipulating the facts to push an agenda), and (2) organised religion in general, and Christianity in particular, being low-status in academic circles, meaning that ecclesiastical authors suffer even more from (1) than secular.
Dude, Theodore literally says Valens was “a foe to none but them who held the apostolic doctrine”, i.e. "he persecuted everyone on my side, but only people on my side, even though we're the rightful majority and always have been". If someone said that today about an authority -- even if you didn't have any context and only had their testimony see the issue one way or the other -- would you think "This person is clearly being persecuted" or "This guy is a supremacist about his faction"?* I take issue with claiming that doubts about these veracity are about suspicion of organized religion.

*And if you would still think the former, in the context of the modern day -- well, now the conversation gets into Chat territory, and some pretty uncomfortable Chat territory at that, so we should probably just leave it there.
 
Dude, Theodore literally says Valens was “a foe to none but them who held the apostolic doctrine”, i.e. "he persecuted everyone on my side, but only people on my side, even though we're the rightful majority and always have been". If someone said that today about an authority -- even if you didn't have any context and only had their testimony see the issue one way or the other -- would you think "This person is clearly being persecuted" or "This guy is a supremacist about his faction"?* I take issue with claiming that doubts about these veracity are about suspicion of organized religion.
Firstly, it's not as if Theodore is the only ancient source to mention the persecution, so we'd have to assume that not just Theodore, but every Christian writer of the period, was biased in the same way, which is a much less likely proposition.

Secondly, there are in fact examples of states persecuting one religion or political ideology and leaving the rest more or less alone, so it would be rash to dismiss the possibility here a priori.

Thirdly, even if we assume that Theodore was wrong, I don't see why we should jump to the conclusion "Therefore, Theodore was a supremacist about his own faction" and not, say, "Therefore, Valens was persecuting other groups as well, but Theodore didn't notice" (after all, your argument presupposes that it's possible for something to feel like persecution for someone on the receiving end but not to an outside observer).
 
As for the article itself--

Valens may have supported the Homoian communities simply because they were dominant in the East as he became the emperor; it is possible that he aimed to maintain the status quo for the practical reasons and was not involved in doctrinal issues himself. The arsenal that Valens used were confiscations and banishments, the means that his predecessors, pagan and Christian alike, had used. For Nicene churches and bishops, these procedures were persecution, and consequently, Valens’ coercive measures were compared with the previous persecutions by pagan emperors. The label of a persecutor was an effective polemical device as it could targeted against heterodox emperors, magistrates, and ecclesiastical rivals. In the case of Valens, the label of a persecutor has stuck in the ancient and modern historiography for centuries.

This seems to concede that Valens did in fact use "confiscations and banishments" against the Catholics in favour of the Arians, but then says this doesn't count as persecution because (a) Valens' predecessors had done similar things, and (b) Valens was trying to maintain social harmony rather than being interested in Christian doctrine per se. Neither of these is particularly convincing to my mind. (a) Only proves that Roman Emperors had form when it came to persecuting dissident religious groups, which if anything should make us more willing to affirm that Valens persecuted Catholics. (b) Is simply irrelevant -- persecution doesn't cease to be so just because it's done for reasons of social stability rather than out of religious conviction.
 
(after all, your argument presupposes that it's possible for something to feel like persecution for someone on the receiving end but not to an outside observer).
That is pretty standard position actually. It's pretty well documented and understood that members of a faction used to wielding position of power and privilege, or who otherwise believe said dominance is due to them, will often perceive the decline of said power and privilege as being indicative that they are being persecuted. Or will, at the very least, frequently use rhetoric indicating as much.
Secondly, there are in fact examples of states persecuting one religion or political ideology and leaving the rest more or less alone, so it would be rash to dismiss the possibility here a priori.
The issue isn't just that he's claiming that "the state was persecuting one religion and leaving the rest alone", it's saying "the state was persecuting the one religion that happens to be both my own and the dominant faction in society"; at that point, a reasonable person would consider that the person speaking is framing the loss of their faction's privilege as being tantamount to persecution, even if they would not conceive of it so.
Firstly, it's not as if Theodoret is the only ancient source to mention the persecution, so we'd have to assume that not just Theodoret, but every Christian writer of the period, was biased in the same way, which is a much less likely proposition...

Thirdly, even if we assume that Theodoret was wrong, I don't see why we should jump to the conclusion "Therefore, Theodoret was a supremacist about his own faction" and not, say, "Therefore, Valens was persecuting other groups as well, but Theodoret didn't notice"
I would say Theodoret's quote should at least give us some context when looking at the testimony of other writers of the period -- maybe he was atypical in how he conceived Valens' actions in inter-Christian disputes, but I don't see why we should read those testimonies on the assumption that he was.

Anyway, still hoping this isn't too "current" political, but it seems to have avoided crossing that line so far.
This seems to concede that Valens did in fact use "confiscations and banishments" against the Catholics in favour of the Arians, but then says this doesn't count as persecution because (a) Valens' predecessors had done similar things, and (b) Valens was trying to maintain social harmony rather than being interested in Christian doctrine per se. Neither of these is particularly convincing to my mind. (a) Only proves that Roman Emperors had form when it came to persecuting dissident religious groups, which if anything should make us more willing to affirm that Valens persecuted Catholics. (b) Is simply irrelevant -- persecution doesn't cease to be so just because it's done for reasons of social stability rather than out of religious conviction.
Maybe it would help to distinguish between "persecution" and "targeted persecution"? In any event, I think the issue of Valens' lack of concern for Christian doctrine is relevant, in that it indicates that his actions against Nicene Christians were not done against them as a faction; and it may even be possible that what constituted an "Arian" or an "Orthodox" was decided by the authorities after the fact to be, in part, determined by who Valens did or didn't prosecute.

If Valens was mainly concerned about social harmony within his empire, and that harmony included the goodwill of the Arians, then it would make sense that a significant number of clergy who strongly disagreed with this, and considered the unity of the faith as dictated by Nicea to be of the utmost importance to their faith... well, to my mind anyway, it wouldn't be surprising in the least that they would consider the actions of their emperor that frustrated their efforts at unity to be persecution in and of itself. And then, if said emperor went and got killed and his army destroyed in a battle with the barbarians -- and then for the emperor who succeeds him to do everything they hoped Valens had been doing instead, and then some, persecuting and smashing all influence of the heretics, jews, and pagans that stood in the way of their unity -- well, that would just go to further prove that God agrees with their position.
 
That is pretty standard position actually. It's pretty well documented and understood that members of a faction used to wielding position of power and privilege, or who otherwise believe said dominance is due to them, will often perceive the decline of said power and privilege as being indicative that they are being persecuted. Or will, at the very least, frequently use rhetoric indicating as much.
I think this is a misunderstanding of the religio-political situation in the Eastern Empire. Arianism had been supported by Roman Emperors in the east since soon after Nicaea -- even Constantine seems to have been leaning towards this position by the end of his reign (at any rate, he was, IIRC, baptised by a priest with Arian views). Before that, Christianity had spent most of the time since Jesus' death being either persecuted or tolerated but kept well away from any official influence. At most, Catholic Christians in the East had enjoyed a position of power and privilege for about ten years (from Licinius' defeat in 324 to the twilight years of Constantine's reign) out of the previous 350.
 
I think this is a misunderstanding of the religio-political situation in the Eastern Empire. Arianism had been supported by Roman Emperors in the east since soon after Nicaea -- even Constantine seems to have been leaning towards this position by the end of his reign (at any rate, he was, IIRC, baptised by a priest with Arian views). Before that, Christianity had spent most of the time since Jesus' death being either persecuted or tolerated but kept well away from any official influence. At most, Catholic Christians in the East had enjoyed a position of power and privilege for about ten years (from Licinius' defeat in 324 to the twilight years of Constantine's reign) out of the previous 350.
Fair point. I won't belabor the issue of whether the religious policies of Valens amounted to "persecution" anymore.

And I won't because I don't think it's especially relevant to the topic at hand -- namely, whether an Emperor Valens who wasn't devastated by Goths at the Battle of Adrianople would be doomed to be toppled from power by religious friction within his empire. I think he certainly would be dealing with rebels -- his deference to the Arian majority in his realm means that at least a fair number of Nicene Christians are going to chafe at his authority, and it doesn't seem likely that Valens is going to be especially gracious in dealing with said "chafing". The question remaining, then, is how well (or poorly) did Valens truly perform as a military commander?

Now I do realize the example of Adrianople is prominent when we think of Valens as a military leader, and likely for good reason; but is it enough, by itself, to conclude that he would not be up to the task of crushing Nicene rebels? What about other military commanders who died in said battle (like Traianus) or others (like Theodosius)?

Thanks.
 
And I won't because I don't think it's especially relevant to the topic at hand -- namely, whether an Emperor Valens who wasn't devastated by Goths at the Battle of Adrianople would be doomed to be toppled from power by religious friction within his empire.
Oddly enough, whilst the late Roman Empire had plenty of doctrinal controversies, I can't think of any religious wars. Whatever fate ends up befalling Valens, then, I don't think a rebellion by angry Trinitarian Christians is on the cards.

Though I would quibble with the notion that Arians were a majority, even in the east. Historically, after Theodosius cast his lot in with the other side, Arian Christianity seems to have withered away pretty quickly, at least in Roman territory. This suggests, at least to me, that Arianism owed most of its success to Imperial patronage, and didn't have much penetration amongst the populace as a whole. The barbarians, of course, were another matter -- somewhat ironically, if Valens wins at Adrianople, one of the results would be to notably reduce the number of Arians in the Empire compared to IOTL.
 
Oddly enough, whilst the late Roman Empire had plenty of doctrinal controversies, I can't think of any religious wars. Whatever fate ends up befalling Valens, then, I don't think a rebellion by angry Trinitarian Christians is on the cards.

Though I would quibble with the notion that Arians were a majority, even in the east. Historically, after Theodosius cast his lot in with the other side, Arian Christianity seems to have withered away pretty quickly, at least in Roman territory. This suggests, at least to me, that Arianism owed most of its success to Imperial patronage, and didn't have much penetration amongst the populace as a whole. The barbarians, of course, were another matter -- somewhat ironically, if Valens wins at Adrianople, one of the results would be to notably reduce the number of Arians in the Empire compared to IOTL.
I think if Valens survives the Gothic onslaught of 376 and he's unlikely to be killed in some rebellion... well, OP mentioned his brother Valentinian living to his mid-60's, but we can imagine Valens living at least to his mid-50's; he could easily live another five years, likely more. If the older brother outlives the younger TTL, I wonder if you would see Valentinian trying to put one of his sons on the eastern throne (then leaving the west to his other son)?
 
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