How big can the Roman Empire get?

Question about Britannia...If it's opted between to conquest all of it and to not conquest all of it....Could be more feasible an intermediate option and conquest only the south up to the Thamesis river and keep it as the border? With the rest of the isle left to a serie of allied/vassal tributaries tribal confederations....

The Thames is easily crossable in the West. Doesn't work as a border.

https://s0.geograph.org.uk/geophotos/05/37/96/5379606_b7e7f5f8.jpg
 
@Atamolos

Are you advocating a rule over Assyria and yet leaving Babylonia?

More-or-less. This area would provide a strategic salient from which interventions might be launched into Armenia or Mesopotamia with limited exposure for the province of Syria. Maximum strategic mobility for limited exposure is the key to stable, indirect control of large independent populations.


This has always kinda bugged me. If civil wars were the main cause of the fall of the WRE, then why did it take centuries of civil wars to finally end up with the fall of Rome? What about the constant civil wars of the late republic? They didn't lead to the republic's dissolution, even in the face of powerful enemies like Pontus and their own Italian confederacy. Why did the ERE last for another thousand years in spite of the same type of civil wars? How do you account for the many periods of internal peace in this period (i.e. during the reigns of Severus Alexander, Diocletianus, Constantinus, Valentinianus I, Honorius, and Valentinianus III)? If civil wars were the deciding factor, why did it take sooooo long to take its toll?
 
More-or-less. This area would provide a strategic salient from which interventions might be launched into Armenia or Mesopotamia with limited exposure for the province of Syria. Maximum strategic mobility for limited exposure is the key to stable, indirect control of large independent populations.



This has always kinda bugged me. If civil wars were the main cause of the fall of the WRE, then why did it take centuries of civil wars to finally end up with the fall of Rome? What about the constant civil wars of the late republic? They didn't lead to the republic's dissolution, even in the face of powerful enemies like Pontus and their own Italian confederacy. Why did the ERE last for another thousand years in spite of the same type of civil wars? How do you account for the many periods of internal peace in this period (i.e. during the reigns of Severus Alexander, Diocletianus, Constantinus, Valentinianus I, Honorius, and Valentinianus III)? If civil wars were the deciding factor, why did it take sooooo long to take its toll?

What would be done of Babylonia then? You do not say that the Arsacids continue to rule Baylonia unopposed, correct?
 
What would be done of Babylonia then? You do not say that the Arsacids continue to rule Baylonia unopposed, correct?

Not unopposed. That's what I mean when I say "strategic salient". It doesn't matter if Rome doesn't exercise exclusive control over Mesopotamia, so long as they are strategically well-placed to make armed interventions against Ctesiphon. This could be done to install a pretender to the Parthian throne, to launch retributive campaigns into Parthia proper, or to simply put pressure on any incumbent government. I think it's a misconception that neutering the Parthians would automatically blunt any future Persian power. It was the Romans constantly hammering the Parthians that put so much pressure on their own regime (which eventually led to the rise of the Sassanids), so an intact Parthia would actually be more of a boon to Rome than a destroyed one.
 
The best Julio-Claudian POD IMO is to have Augustus grandsons Gaius and Lucius survive there deaths in 2 and 4 AD. You will have a complete Julian dynasty were you can kick out the ineffective Claudian part of the family. Tiberius a bitter man who hates the idea of the Principate. Claudius is a very weak man who is easily swayed by his wife and freedmen. The less said about the Germanicus the better. Claudia Livillia is just a classic Claudia. The only effective member of the part funnily enough of the house is Nero Claudius Drusus, Tiberius son, even though he seemingly like to slapped anyone around him...

Who’s to say the Julian branch wouldn’t have been worse? Gaius, from what little we can see, was spoiled, impulsive, craven and, ultimately, weak. After his fatal wound, he had a complete mental breakdown, even begged Augustus to let him live in peace with no further responsibilities. That’s no great emperor material there. Lucius? Who knows, he died way too soon. In any case, even if Gaius had lived, the family would have still had the Claudian branch in it. Livilla was married to Gaius after all.

If Claudius had been such a weak fool, why did Agrippina think it wiser to have him killed? He had a way tighter control on things than tradition would have us believe. Marrying Agrippina was a mistake he should have avoided, but there’s a lot more things he did right that we can excuse him for that. And what’s so wrong about Germanicus?

Admittedly, things could have gone possibly better for the Julio-Claudians
if Drusus, Tiberius’ brother, survived. That is, if he had grown out of his Republican sympathies.

A Julio-Claudian POD would be way too early on to adress the empire would have in its future. The civil wars did play a part, but it wasn’t just them, or the fact that the empire lacked a long standing dynasty whose dignity could be enough to prevent usurpations. There’s a lot more reasons, not least that, as history dictates, every great empire’s meant to fall sooner or later. The Roman empire actually lasted way more than a dominion of such entity usually did. Certain conditions could prevent the fall of the Western half in 476 CE, but they’d just delay the inevitable, and not by much.
 
-- The inevitable Persian attempt to get back Mesopotamia must then be staved off. This will be very costly. If it is done, however, whoever's in charge of Persia is screwed. It was costly for them, too, but Rome has taken away their wealthiest region; their economic heartland. Rome has just won the big rivalry. Each passing year will now strengthen Rome relative to Persia, as Mesopotamian revenue flows to Rome rather than to Persia.

-- The next and final step in the east is to carve client kingdoms of out Media and Susiana. Since Rome is a distant benefactor to them, whereas a resurgent Persia would be a more near-by overlord, it's in their interest not to stab Rome in the back. This gives Rome a buffer to any invasions from Central Asia that approach via the Persian highlands. (Also, expand those trade ports to basically follow the whole coast of Arabia, so that Rome can safely move to and from Mesoptamia by sea.)

So not only does the sitting emperor has to show that being closer to Rome than Persia is more beneficial, Rome has to also defend Mesopotamia without significantly weakening Persia because I can’t see Roman interests in seeing another unified polity from Zagros to Indus, i.e., the Hephthalites and the Arabs. The geopolitics just became more delicate and one incompetent and/or ambitious leader can start the dominoes.

A Julio-Claudian POD would be way too early on to adress the empire would have in its future. The civil wars did play a part, but it wasn’t just them, or the fact that the empire lacked a long standing dynasty whose dignity could be enough to prevent usurpations. There’s a lot more reasons, not least that, as history dictates, every great empire’s meant to fall sooner or later. The Roman empire actually lasted way more than a dominion of such entity usually did. Certain conditions could prevent the fall of the Western half in 476 CE, but they’d just delay the inevitable, and not by much.

I agree that all empires are meant to fall but I disagree with the premise that the POD is too early to delay the inevitable. Caesar and Augustus not withstanding, the Julio-Claudians could have done a lot better and lasted the dynasty a good 200 years and alleviate two problems the empire constantly had, establishing smoother transfers of power and securing core territories by expansion. Sure a longstanding dynasty doesn't prevent incompetence and usurpation but more legitimacy doesn't hurt and lessens the risk your soldiers handing your head to the highest bidder or your most powerful general. Sure future Julio-Claudian emperors could have been incompetent but they could have also been great because there's the Nerva-Antonines who by all considerations, I call a wank in these boards and besides, Rome can take a few incompetent emperors as OTL has shown. I guess what I'm simply saying is less bad is more good and certainly doesn't hurt, which is good for the empire's longevity.
 
This has always kinda bugged me. If civil wars were the main cause of the fall of the WRE, then why did it take centuries of civil wars to finally end up with the fall of Rome? What about the constant civil wars of the late republic? They didn't lead to the republic's dissolution, even in the face of powerful enemies like Pontus and their own Italian confederacy. Why did the ERE last for another thousand years in spite of the same type of civil wars? How do you account for the many periods of internal peace in this period (i.e. during the reigns of Severus Alexander, Diocletianus, Constantinus, Valentinianus I, Honorius, and Valentinianus III)? If civil wars were the deciding factor, why did it take sooooo long to take its toll?
Rome has no rivals after Augustus does his conquest. Nobody was able to destroy Rome like Rome had done 200 - 100 BC.

Come on Pontus? Pontus wasn't some great powerful enemy. A regional Power sure but it wasnt powerful. The Romans always had bigger fish to fry when dealing with him.

The two major sets of Republican civil wars had political instability inbetween but no civil wars. The "length peaceful" reigns are not free of internal civil war. Just look at list of civil wars after 218 AD.

It was the constant civil wars and the political environment that no one was safe, ever. That brought down the WRE. In the last century the ERE had allot less revolts then the west which created political stability. The gothic war is a perfect example of the inefficiency of the Dominate. You more or less the same thing Caesar faced in the Helvetii migration in 58 BC. Which he deals in less then a year on his own...
 
You can also imagine a chinese like roman empire: it grows, then it fall apart in pieces, each one expand on their own area, then one of these parts conquer the others.
For exemple:
A surviving Germanicus conquer Germania Magna to the Elbe allowing his brother Tiberius to eliminate the marcomani and making a northern client state («Saxemarca»?) from the Elbe to the baltic.
Next generation of emperors can conquer Mesopotamia, but that means an increase of the armies, so we can imagine a revolt based in the Mitra cult, very common among the soldiers.
When the revolt is crushed maybe the new emperor decide to convert (or legalize) the more pacific christian cult and forbide the mitraism and other "dangerous cults". To control the territory and the armies other political reforms can be implemented, like extended citizenship and regional senatus, which could increase romanization.
After some generations a mad emperor that consider himself a living god persecute the christians and eliminate the local senatus, even the Rome's one, producing a tripartition of the empire: a Holy Roman Empire in the center and north (a theocracy ruled by the roman bishop and protected by a german general who will became Emperor «à la Charlemagne»), a Second Roman Republic (based in Gallia, Hispania or Africa and stablished by some patrician-senatorial families who scaped from Rome) and a New Roman Principate in the east (maybe founded by a surviving member of the imperial family).
After centuries of war one of the states may conquer the others... or not, allowing a reason for an exploration era around the IX or X century.
 

Albrecht

Banned
You can also imagine a chinese like roman empire: it grows, then it fall apart in pieces, each one expand on their own area, then one of these parts conquer the others
Interesting. Like the Gallic Empire during the Crisis of the Third Century.

Eastern Anatolia was taken over by the Palmyrene Empire. But in an ATL, I could imagine the breakaway of Greek speaking regions taking Syria, Judea, Egypt and Cyrene with it. The capital could be Antioch, Alexandria or any major city in Anatolia. This empire could then expand into parts of Persia and even Russia/Ukraine. This happening before the Crisis of the Third Century would be very interesting.
 
So not only does the sitting emperor has to show that being closer to Rome than Persia is more beneficial, Rome has to also defend Mesopotamia without significantly weakening Persia because I can’t see Roman interests in seeing another unified polity from Zagros to Indus, i.e., the Hephthalites and the Arabs. The geopolitics just became more delicate and one incompetent and/or ambitious leader can start the dominoes.



I agree that all empires are meant to fall but I disagree with the premise that the POD is too early to delay the inevitable. Caesar and Augustus not withstanding, the Julio-Claudians could have done a lot better and lasted the dynasty a good 200 years and alleviate two problems the empire constantly had, establishing smoother transfers of power and securing core territories by expansion. Sure a longstanding dynasty doesn't prevent incompetence and usurpation but more legitimacy doesn't hurt and lessens the risk your soldiers handing your head to the highest bidder or your most powerful general. Sure future Julio-Claudian emperors could have been incompetent but they could have also been great because there's the Nerva-Antonines who by all considerations, I call a wank in these boards and besides, Rome can take a few incompetent emperors as OTL has shown. I guess what I'm simply saying is less bad is more good and certainly doesn't hurt, which is good for the empire's longevity.

I’m not saying that a stable dynasty wouldn’t have helped, it would have, but who’s to say the dynasty wouldn’t have collapsed anyway even if Gaius had survived? Or Drusus? There’s no POD for the Julio Claudians that can absolutely guarantee their permanent security, let alone a longer survival for the empire.
 

Albrecht

Banned
Centralised economy is also a problem for much expansion. Concentration of power and wealth is an another. If you find a way to overcome these, the expansion into larger regions could be thought of.
 
Rome has no rivals after Augustus does his conquest.

The Parthians and the Sassanids would beg to differ.



The two major sets of Republican civil wars had political instability inbetween but no civil wars. The "length peaceful" reigns are not free of internal civil war. Just look at list of civil wars after 218 AD.

Between 49 and 30 hundreds of thousands of Romans died and the nobility was completely decimated. How is that a civil war without a civil war?
 
The Parthians and the Sassanids would beg to differ.
Please. The Parthian can't even assault the well fortified cities of Syria. They were no real treat. When did the Sassanids march into Italty or got even close? Like when the Romans would march down Mesopotamia to sack every city over and over again in the 100-200 AD.

They are no real Doomsday treats like Hannibal was 200-500 years before the Late 400 early 500 century when the Romans have had constant civil war for 200 years and there isn't a person alive who hasn't lived without one.

Between 49 and 30 hundreds of thousands of Romans died and the nobility was completely decimated. How is that a civil war without a civil war?
Yes the civil wars were brutal, I never said they weren't. But there was a long period with no civil wars after the Republican ones and until the death of Commodus they were short when they did happen.
 
Please. The Parthian can't even assault the well fortified cities of Syria. They were no real treat. When did the Sassanids march into Italty or got even close? Like when the Romans would march down Mesopotamia to sack every city over and over again in the 100-200 AD.

They are no real Doomsday treats like Hannibal was 200-500 years before the Late 400 early 500 century when the Romans have had constant civil war for 200 years and there isn't a person alive who hasn't lived without one.

And yet the Romans, at the time of Severus, had around 10 legions stationed in the whole Eastern frontier, a third of the whole army. The Romans were strong enough to contain the Parthians, but the Parthians were strong enough that they needed to be contained in the first place, with no hope of conquering them. They’re a threat because the Roman empire could not allow itself to move too many legions from the Eastern frontier lest they risk suffering an invasion, a potentially disruptive one. It doesn’t mean anything that they couldn’t hope to reach Rome, they could sweep the whole Eastern sector if allowed to, and they almost did in 40 BCE, when it was poorly guarded due to civil wars. Same for the Sassanids in 260, when a Roman army was completely destroyed at Edessa, Gallienus had to rely on a local military potentate to fend them off, or else, amid all the chaos he found himself in, he’d have been unable to.


Yes the civil wars were brutal, I never said they weren't. But there was a long period with no civil wars after the Republican ones and until the death of Commodus they were short when they did happen.

That was more because of Augustus’ political brilliance than anything. Had he died younger than he did, who knows what could have happened.
 
And yet the Romans, at the time of Severus, had around 10 legions stationed in the whole Eastern frontier, a third of the whole army. The Romans were strong enough to contain the Parthians, but the Parthians were strong enough that they needed to be contained in the first place, with no hope of conquering them. They’re a threat because the Roman empire could not allow itself to move too many legions from the Eastern frontier lest they risk suffering an invasion, a potentially disruptive one. It doesn’t mean anything that they couldn’t hope to reach Rome, they could sweep the whole Eastern sector if allowed to, and they almost did in 40 BCE, when it was poorly guarded due to civil wars. Same for the Sassanids in 260, when a Roman army was completely destroyed at Edessa, Gallienus had to rely on a local military potentate to fend them off, or else, amid all the chaos he found himself in, he’d have been unable to.
It's also worth noting that although Parthia/Persia can't reach Rome itself, taking the rich Eastern provinces would have have been a death blow to the Empire. Their revenues were necessary to pay for the legions.
 
I have said it before (many times), and I'll say it again (presumably also many times): Rome should have played for keeps with Mesopotamia. That's priority number 1. I know it's going to be absurdly costly, but the profits will outweigh the costs. Mesopotamia was, by itself, more economically profitable than the entire Western Empire. It will pay for itself even if the cost of defending it is absurdly high-- and keeping it out of the hands of whoever rules Persia ensures that this rival is forever critically weakened.

Abandon Britain if you must. In fact, do that anyway.
Britain was always a big damned money-sink and breeding ground for usurpers and trouble-makers. Just secure the Isle of Wight and the Isles of Scilly (for the tin), and use the fleet stationed in north-western Gaul to stave off piracy.

I heard on an old "Fall of Rome" podcast that at one point an eighth of the Roman Army was stationed in Britain. If that's true then all the more reason to pull up stakes and focus the resources elsewhere.
 

Skallagrim

Banned
I heard on an old "Fall of Rome" podcast that at one point an eighth of the Roman Army was stationed in Britain. If that's true then all the more reason to pull up stakes and focus the resources elsewhere.

Let's put it this way: if you have 28 legions, and three of them are permanently wasted on that one island (and at times this number has to be upgraded to four), then something is going wrong.
 
I'd say that under Antoninus Rome can be big enough that it includes Germania up to the Elba, all of Dacia, Mesopotamia and maybe some other chunks of land here and there.
IMO places Britannia and Germania would be massive sources of debt and instability, while Mesopotamia would be the exact opposite (Maybe not for the instability.), so I'm not sure about how long Rome can last in such a TL.
 
I mean, the obvious statement is - GLOBAL. But that obfuscates the rather telling questions of "How?".

If you want a single Empire with deep control, you're going to have problems, especially if that is your definition of "Empire".

If we want to include decentralised power, or federal systems, or even a Soft Power Empire, we make our lives much easier.

There was a thread that was discussing ways for the Empire to fall back on borders in order to survive. Now if we go with the assumption that the Empire was a beast that needed to expand to survive, this doesn't really work, unless we're also changing the nature of the Empire. Then we can have an Imperial Core that focuses on the Med that is easily access, close by, etc. This means that Britain and N.Gaul are those parts of the Empire that are distant, expensive, and regular grounds for usurpations. You could change the method of Roman expansion, and with an easily defended Imperial Core that lets go of Britain and Gaul (letting them go as ROMAN allied states) we then have a Soft Power Empire, as the economic power of the Imperial Core helps keep the allies in line, whilst ensuring the Imperial Core can hold. Gaul and Britain veer off and are able to respond to their local problems with some minor assistance when letting go, and you have a new model for Imperial Expansion on your hands. Establishing Allied States, that are then tightly bound economically.

You could harden this approach and have the Allied states bound with the Imperial Core, a form of allied stratocracy. "We all agree it makes a lot of sense to push the frontier in Germania" for example, establishing a new Member, and resolving issues. For example, establishing a Roman Germania from a mix of British raiding bases, Gallic forward bases, and an influx of recruits and colonists from the Imperial Core. They're able to respond locally, relatively freely, negating the communication problem - their main task developing military stability.

That sort of model could be duplicated relatively successfully. Does it have potential for infighting? For sure, but it can be applied flexibly. Need an ally to handle the problem of Steppe invasions? Establish one in Taurica, and provide them the subsidy and recruits to fight the problem there. Plus, it doesn't need to be Roman initially - just become part of Roman Soft Power long enough to be subsumed.

If you go with this model, you can start having expenditions past Egypt that can act as Soft Power Allies in Yemen, etc.


The biggest advantage of this, is that the long-term connections can make any annexations made during an internal conflict more tolerable. If you have a Germania, and Britannia is secure, they don't NEED to be outside the Imperial Core any more. If there is a better centre for the Empire, it can emerge, it could emerge that the Imperial Core has two neighbour states of the Northern Roman Empire (Gaul, Germania, Britannia), and the Southern (Yemen, Ethiopia, Somalia). The three states are still pretty tightly bound.

Sorry if that seems a bit of a dodge, but if you expand the parameters to "Established the world order" then you make your task much easier, until you hit groups like Persia, India and China - whom you'll have to fight on that level, which is a slightly different form of politics. But if you can localise, adopt, integrate, then you can expand your influence much more easily than marching in endless legions.
 
The latter isn't easy to go beyond one or two provinces/regions than the OTL. The successfully Romanized lands were parts of Iberia and the entire Gaul(today France). Beyond these, Romanization didn't completely sink into any other province and they did retain their local identities and cultures, for the most part, than identifying with the Romans. Examples for this are most of the Balkans, Greece and Anatolia, Levant, Egypt and North Africa. The reason for this is while the Gauls and the Pre-Roman Iberians were tribal and loosely structured and hence found it profitable to join the Roman civilization, the ones in the Non-Romanized provinces(except Balkans) already had a rich culture, large population and Ancient civilizations. No reason to abandon your rich heritage and no need for the Romans to tamper with these as they were mostly cool with other Pagan religions and societies and they also didn't want to risk a destabilization. It would rather be that the Romans were influenced more than the other way round.

The interesting part about Romanisation and North Africa is that the Punic language continued to spread under Rome, and spread until the 3rd century or so in most places before it began to be supplanted by Latin. Even deep within the Atlas Mountains we can find auxillia writing in Punic in the 4th/5th centuries as well as inscriptions in civilian areas, although it seems to be in decline by then. Most of the centerpoints of Punic culture like Carthage itself and some coastal areas of North Africa are thoroughly Romanised by Late Antiquity, although certainly there were areas the Punic language held on.

I would not consider the Mauretanian provinces west of Africa and Numidia to have had any richer a pre-Roman culture than the Balkans. They were occasional allies of Carthage, occasional foes, and rather tribal the entire time (well into the Roman period, let alone what the Berbers got up to during Arab times)--in that sense it was more like Iberia than anything else. Rome could've certainly done better there--more veteran's colonies perhaps (like you see in Iberia), although those certainly existed. Maybe those would've been established had they conquered south from Volubilis. I don't think they could've permanently subdued or assimilated the Berbers--likely you'd have many pockets where Berber language and identity held on, as Romanised (and later Christianised) as it may appear on the surface, which would pose a huge threat to the provinces if provoked. The Arabs certainly couldn't.

-- Once all the above is done, and assuming the geopolitical situation allows for it (i.e. no threats on the horizon), you can then start thinking about actual expansion into Britain, or into more firmly turning some allied North African peoples into clients.
Why so late in conquering the rest of North Africa (well, just Mauretania)? It's no different from what the Romans are already doing in Mauretania Tingitania, will have a similar economy (pastoralism, agriculture along the Atlantic plain of Mauretania), and help secure Volubilis and beyond against potential raids. The challenging expansion here is into the Anti-Atlas and Sous Valley, which does offer argan oil as a resource and would complete the conquest of the fertile parts of North Africa but is far more mountainous and challenging. Still, it's no worse than Caledonia, and unlike Scotland a "Hadrian's Wall" equivalent can be much simpler and just guard the mountain passes. Rhysaddir (modern Agadir, although since Agadir has the same etymology as Cadiz in Spain, Gades might be what the Romans call it) could operate as a Roman-controlled fort/seaport and give a semblance of Roman control to help confirm the local Berber tribes as Roman clients should they not decide to conquer the area.

While it will take a legion garrisoned there (in Volubilis maybe), it offers additional fishing grounds (including for the snails which give the rich purple dye) and additional grain and pastoralism like the rest of North Africa. There is also some precious metals in the region too, and in the Sous area argan oil. The Romans only face the Berber tribes in the mountains once they secure the best land along the coast and rivers, and I think they can be more or less placated like the Romans did in the British Isles. Instead of risky and aggressive campaigns against Persia or the Germanic peoples, it may be best if the Romans go for Mauretania where once they subdue the initial opposition and garrison the province, they'll keep it well into Late Antiquity. It's also fertile grounds for developing a trans-Saharan trade with Ghana or trading with the Canaries (more of that purple dye) who can be turned into a client like the Irish clans. It will also force new development in Roman shipbuilding to make better ships for the rough Atlantic. So geopolitically and economically I think it makes as much sense as Dacia and is simpler and easier to do than a sustained campaign in Mesopotamia or Germania.
 
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