WI : The Gallic Release Valve

I'm curious as to what the impacts would be of a massive defence in depth strategy for the Western Roman Empire that used the entirety of Gaul as a playground for foederati - instead of spending money fortifying the length of the Rhine, instead leaving troops in Britannia, Hispania and Italia - fortifying the passes and building coastal defences in Britain.

The principle would be that the Foederati would be negotiated with as per OTL to protect Gaul, but the Romans wouldn't be overly fussed to reassert their authority. Instead, they'd try and use soft-power to keep the Foederati on side (trade, prestige, gold, etc) but having very little problem with Gallic Foederati going to war with each other. Perhaps an arrangement where the Romans would help out the Foederati who were attacked, and only retaking territory when the Romans had the money and manpower to spare.

I think it seems unusual as a strategy, but with Foederati vs Foederati vs Germanics fighting, and the region surrounded, I think it could provide the Empire with one major Italio-Eastern territory, the Fortresses (early Exarchs?) of Britannia and Hispania, and the Foederati territory of Gaul. It shortens the borders (overall), and creates a situation where the Empire doesn't have to defend its Rhine border, but instead both undermines the Germanic people in the region as money isn't being spent on forts to buy wheat, and leaving them to fight amongst themselves.

I'm not 100% but I think it could be a way to save the Empire - even if it does throw Gaul and Germania into possible chaos, which the Empire can take advantage of diplomatically in the meantime, and then invade once they've recovered from plagues and political issues.
 
Wouldn't it be more prudent to use Britannia as a safety valve instead of Gaul? The foederati can be used to keep each other in check in addition to protecting the Empire's assets from being used by possible usurpers or seized by barbarian invaders.
 
Wouldn't it be more prudent to use Britannia as a safety valve instead of Gaul? The foederati can be used to keep each other in check in addition to protecting the Empire's assets from being used by possible usurpers or seized by barbarian invaders.

I can see why you'd suggest it considering the relative economic value of Gaul compared to Britannia, but I think that the pull factor of Britain isn't that high, discouraging passive invasions. I don't think anyone will say that the Angles Jutes or Saxons were major players compared to the Franks, as such they took the easier pickings. Gaul has more of a pull factor, attracting more competitors to the region. The Romans would have to actively be shipping people over, and we saw ITTL that doing so didn't make Gaul safer, in fact it isolated Gaul in the long run, with no reinforcements in the North.

In addition, the comparative ease of crossing the Rhine compared to crossing the Channel means that the threshold for an invasion is lower - rather than have an army and a way to transport them, invaders can cross the river. That passive risk from the Northeast (whilst theoretically being contained in the SE, SW and NW) helps prevent the Foederati fully consolidating - look at OTL history, group after group invaded from Germania into Gaul and onwards once the Rhine defenses were passed, whereas now any invader has to deal with the previous invaders who are fighting more existentially than the Romans ever realized they were, whilst backed in the worst cases by a Roman army that is more prepared, as it has the time to prepare the expedition to counter an invasion of Gaul, whilst not having their own homes raided.

Plus, unlike Britannia, Gaul is harder to consolidate because of the Rhine. Invasions can come in more easily, and if it is too close to unifying, the Romans can invade from three sides and upset the balance or reassert control. In constrast whilst Britannia had the Angles Jutes and Saxons, after that they didn't really have anyone interested in a real invasion till the Viking period, and there would only be one front for an invasion, the South.

I personally like to imagine it like a medieval castle on a strategic scale - the Rhine is the first wall, and Hispania, Italia and Britannia are three internal walls to defend/attack from, forcing an enemy to fight on multiple fronts, twisting the traditionally Roman problem of resources along a long border around and putting it on the Gallic Foederati.
 
I'm curious as to what the impacts would be of a massive defence in depth strategy for the Western Roman Empire that used the entirety of Gaul as a playground for foederati - instead of spending money fortifying the length of the Rhine, instead leaving troops in Britannia, Hispania and Italia - fortifying the passes and building coastal defences in Britain.
Giving the relative strategical and financial importance of Gaul above Britain, it makes little sense.
Not only Gaul represented a fairly safe "shield" when it come to protecting Alps (relatively to the pretty much broke Illyricum), but a lot of militia recruits and instituionals came from Gaul, as point the fierce attitude of Gallo-Roman nobility at the first sign of WRE trying to abandon Gallic regions to themselves in the 440's/450's up to giving up on Rome for a large part afterwards.

Keeping Britain while loosing Gaul serves absolutly NO purposes : at best you'd end up financing a beggining for fortification in the island that you won't be able to pay as soon as Gaul is overtaken by foedi and aristocratic split-ups. And then Britain ends up the same since you can't pay anyone to defend it.
It's really the less sound stratefgical idea one could have in the region since Frisian Islands TL.
 
I don't think anyone will say that the Angles Jutes or Saxons were major players compared to the Franks
I will, tough.

You're making an important, if common, anachronical confusion there, taking as granted that the major players of the early Vth will be the same than in early VIth.
Long story short, most of foedi in the early Vth, were relatively limited in size and desunited. How it worked up in the Vth made some building-up enough their power to reach regional hegemonies (Goths in Aquitaine, Franks in Belgica, Burgondians in Viennensis, etc.).
As for what matter Saxons, they extablished a presence in Gaul way since the IVth (the "Saxon shore" indeed was present on both sides of the Channel) and rivaled with Franks for a while for the domination of the North-Western shores (Carolingians used saxon levies from modern Normandy up to the late IXth), and as it happened with Norse in the IXth, you'd likely to see a back-and-return relationship.
I'm astonished you're not reckognizing the threat of a Saxon build up in the continent (meaning Saxons would have more ressources while still ane stablished presence on both sides of the Channel) leading ato a much likely possibility of a Saxon hegemony in the channel leading to a takeover in southern England.

I would point, furthermore, that an important powerbase for powerful VIth century Barbarian kingdoms resided in their capacities to integrate Roman militia (administrative, military, legitim or self-nominated) at their service (as Euric's policies can point, but that's something more or less systematical, which explain the weakness of Odoacer's Principate IMO).
By depriving Gaul of armies, regardless of the reason, you basically end up with weaker foedi mixed up with local Gallo-Roman aristocracies, not unlike the late Vth situation except that (technically, because it's really hard to have such situation really arising) no one in place can really take opportunity quickly.

Conservsely, a pauperized, raid-riddened Britannia with armies and fortified places unable to be maintained trough payment is a golden opportunity for any strong enough Barbarian forces (there Saxon) to claim the provincial service of whatever remain of militia (assuming Britto-Romans doesn't deal with it as IOTL) there.

In addition, the comparative ease of crossing the Rhine compared to crossing the Channel means that the threshold for an invasion is lower
I'm not sure you really well studied the question : Rhine border tended to be one of the most "safe" limes (as much as one could be said to be so, of course) of Late Romania : the 407 expeditions tend to overshadow this a bit, but thanks to the presence of relatively loyal foedi and roman armies AND structural assets, it never nearly went there the point of Danube or North Sea in terms of "why should we even bother".
The relative safety of the Rhine limes more or less survived the Roman Empire, allowing IOTL the Frankish regnum to not deal with an overbearing pressure as it happened with Italy (in its largest sense).

I don't think you're giving enough credibility to the maritime Barbarian threat (Saxon, Gaelic, Pictish, Gothic, etc.) piracy are yet known features (which provoked the settlement of Saxons in North Sea and Channel as a buffed coast guard in the IVth).
Most of the issue when it came to maritime invasion resided less into the capacity of Barbarians to project themselves trough seas, but the capacity of Roman fleet (essentially ERE in the Vth) to cut them down or their supplies lines when attempting this.

Giving you have no real Roman naval force able to do that in North Sea, it wasn't an issue.

I think, on a more or less related point, that ignoring the Gaelic and Pictish threat ITTL, when it provoked the large use of Saxon and Northern Sea people in post-Imperial Britain, to be an issue with your OP.
Assuming that North Sea peoples doesn't go immediatly in Britain (or that the ones already settled in the island since decades doesn't move for any reason), you'd still have to deal with that with a pretty much thin and collapsing system.

I personally like to imagine it like a medieval castle on a strategic scale - the Rhine is the first wall, and Hispania, Italia and Britannia are three internal walls
Assuming Vth Empire have both the time and the ressources to fortify litterally everty diocese border (it doesn't, it's so comically doesn't), there's still the problem that most of foedi didn't as much invaded out of nowhere, than they were displaced trough treaties : a threatening Barbarian forces would eventually be given the oppiortunity to settle in a sanctuarized province in spite of its defenses just for Rome to get away with it (a bit like Aquitaine and Goths). Heck, they would probably even more be given these areas would it be only because Romans would need forces to fend off others Barbarians and ambitious foedi.
 
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Deleted member 97083

You might need an entirely different 5th century Roman Empire for them to consider a strategy so based in realpolitik. The Roman Emperors have to have the concept of pan-imperial grand strategy that they did in the 1st centuries BC and AD. They were also close to this kind of thought at the beginning and end of the Crisis of the Third Century, as well as during Constantine. But with a POD that far back, you can change other factors to fix the Roman Empire, and they wouldn't need to abandon Gaul which was an important recruiting ground for Roman troops.
 
Giving the relative strategical and financial importance of Gaul above Britain, it makes little sense.
Not only Gaul represented a fairly safe "shield" when it come to protecting Alps (relatively to the pretty much broke Illyricum), but a lot of militia recruits and instituionals came from Gaul, as point the fierce attitude of Gallo-Roman nobility at the first sign of WRE trying to abandon Gallic regions to themselves in the 440's/450's up to giving up on Rome for a large part afterwards.

I put forward my justification for my choice of Gaul over Britannia for the idea above, so I won't repeat myself. I wasn't aware of that reaction, I expected something like that would happen - I'd rule out compensation to alleviate their concerns as that would be a laughable idea - that would bankrupt the Empire. For me the major loss is the recruitment - if that can be relocated to Britannia, Hispania and Italia in some way then I'd want to include it in such a strategy. (Doing that would probably bankrupt the Empire too, but at least it would have the benefit of providing manpower).

Keeping Britain while loosing Gaul serves absolutly NO purposes : at best you'd end up financing a beggining for fortification in the island that you won't be able to pay as soon as Gaul is overtaken by foedi and aristocratic split-ups. And then Britain ends up the same since you can't pay anyone to defend it.
It's really the less sound stratefgical idea one could have in the region since Frisian Islands TL.

I'd be intending to fund it through having fewer fortifications than the Gallic Limes required. Do I have the numbers - no, so it would only make sense from a purely fiscal perspective if the savings were large enough, but it does have to be considered alongside the forces available, if the Roman Empire is having to consider withdrawing from Britannia to protect Gaul then it suggests they knew that the Gallic Limes were becoming increasingly impractical to defend with their current strategy.

I will, tough.
Ok, colour me intrigued.

You're making an important, if common, anachronical confusion there, taking as granted that the major players of the early Vth will be the same than in early VIth.
Long story short, most of foedi in the early Vth, were relatively limited in size and desunited. How it worked up in the Vth made some building-up enough their power to reach regional hegemonies (Goths in Aquitaine, Franks in Belgica, Burgondians in Viennensis, etc.).
As for what matter Saxons, they extablished a presence in Gaul way since the IVth (the "Saxon shore" indeed was present on both sides of the Channel) and rivaled with Franks for a while for the domination of the North-Western shores (Carolingians used saxon levies from modern Normandy up to the late IXth), and as it happened with Norse in the IXth, you'd likely to see a back-and-return relationship.
I'm astonished you're not reckognizing the threat of a Saxon build up in the continent (meaning Saxons would have more ressources while still ane stablished presence on both sides of the Channel) leading ato a much likely possibility of a Saxon hegemony in the channel leading to a takeover in southern England.

No, I honestly clear forgot about the Saxon Shore in Gaul. Ideally I'd prefer to see my scenario implemented earlier so that the Saxons don't have a power base in Britannia, but that would be down to exactly when this idea would be implemented (if at all, I won't lie, you're somewhat pummeling the idea).

I'm not sure you really well studied the question : Rhine border tended to be one of the most "safe" limes (as much as one could be said to be so, of course) of Late Romania : the 407 expeditions tend to overshadow this a bit, but thanks to the presence of relatively loyal foedi and roman armies AND structural assets, it never nearly went there the point of Danube or North Sea in terms of "why should we even bother".
The relative safety of the Rhine limes more or less survived the Roman Empire, allowing IOTL the Frankish regnum to not deal with an overbearing pressure as it happened with Italy (in its largest sense).

I don't think you're giving enough credibility to the maritime Barbarian threat (Saxon, Gaelic, Pictish, Gothic, etc.) piracy are yet known features (which provoked the settlement of Saxons in North Sea and Channel as a buffed coast guard in the IVth).
Most of the issue when it came to maritime invasion resided less into the capacity of Barbarians to project themselves trough seas, but the capacity of Roman fleet (essentially ERE in the Vth) to cut them down or their supplies lines when attempting this.

Giving you have no real Roman naval force able to do that in North Sea, it wasn't an issue.

I think this might have to come down to detailed analysis - as I'm trying to compare the geography of the Rhine vs the Channel, with comparable resources per mile being expended. Implementing a system of fortified towns in the south east and other exposed targets as per Alfred the Great should at least be sufficient, especially if there is at least some sort of real Roman naval force in the North Sea. Admittedly, I don't think a Roman military focused on the Empire proper would do this. Tradition and strategy focused on Gaul for the many reasons you've outlined. But if using Gaul this way was seen as reasonable, the only way Britannia could function is with a huge amount of autonomy, with finances and reinforcements sent from Hispania. This Exarchate of Britannia would have to start thinking like England did post-Vikings. Fortified towns, interception fleets and patrols in the North Sea - and spend the money to do this early on to secure their own coasts and the trade routes with the Med. It also raises the threshold cost of an invasion, whilst not majorly increasing the benefit of doing so - which creates an effective deterrent at a lower cost, or a greater one at a higher cost. (The fact I'm arguing that its easier to protect Britain because its poorer is hurting my own head, despite the logic.) - Perversely, the Exarchate getting autonomy and resources to defend itself to a comparable level to Gaul could solve several of their local problems.

Assuming Vth Empire have both the time and the ressources to fortify litterally everty diocese border (it doesn't, it's so comically doesn't), there's still the problem that most of foedi didn't as much invaded out of nowhere, than they were displaced trough treaties : a threatening Barbarian forces would eventually be given the oppiortunity to settle in a sanctuarized province in spite of its defenses just for Rome to get away with it (a bit like Aquitaine and Goths). Heck, they would probably even more be given these areas would it be only because Romans would need forces to fend off others Barbarians and ambitious foedi.

I'm confused, so the Empire can defend the Eastern Alps and the Rhine perfectly fine, but can't fortify/defend the Pyrenees and Western Alps instead? Surely the mountainous terrain is easier to defend than the Rhine? Or is this more the case that the cost of building/modernising fortifications in those regions isn't feasible?

Interestingly the way you describe that just leads me to think that the best Roman solution in the West would always have been to go on the offensive, paying the Foederati with German land, with Roman forces as support/force multipliers. I don't think I've ever read a satisfying answer as to why they didn't - making me concerned that they just had poor strategic planning/poor political choices.

Whiiiiich @Achaemenid Rome has basically stated as I finish this. :D Is it really a case of Pan-Imperial Grand Strategy? In which case, surely there is a reform to the Roman system that would work - compulsory advisors in RealPolitik and Strategy? But surely those existed already?
 

Deleted member 97083

Whiiiiich @Achaemenid Rome has basically stated as I finish this. :D Is it really a case of Pan-Imperial Grand Strategy? In which case, surely there is a reform to the Roman system that would work - compulsory advisors in RealPolitik and Strategy? But surely those existed already?
Influencing enemy kingdoms outside of the borders and playing them off against each other was typical ancient empire behavior. But designating a core imperial province inside the borders as an "engineered hellhole" to weaken enemy tribes seems quite anachronistic.

The emperor would simultaneously have to:
  • have absolute power (not just theoretically absolute but de facto absolute, no disputes with military or nobility)
  • realize that the empire is almost certainly doomed
  • have a desire to save the existence of the empire at all costs, but not care about saving the individual territories of the empire
  • have no attachment to Gaul, or even have a grudge against it and its inhabitants
  • have a new recruitment zone for the empire outside of Gaul, or immediate plans to create one
It seems more like the contingency plan of a 20th century dictator than something an ancient ruler would do.

Maybe if he was a more successful, but more paranoid Maximinus Thrax-like emperor who destroyed the nobility, purged disloyal military officers, and hated Gaul.
 
Maybe if he was a more successful, but more paranoid Maximinus Thrax-like emperor who destroyed the nobility, purged disloyal military officers, and hated Gaul.

To be honest, a more successful Maximinus Thrax who didn't hate Gaul might have stopped the problems that brought up this mad-cap idea :p Even if it was just setting up an internal affairs division of the judiciary after his wars in 236. Considering his dislike of the nobility, and his "common man" status, I'm he doesn't seemed to have acted against judicial/legal injustices. It may even have been enough to prevent the year of six Emperors, and could have been a powerful tool to take out corrupt senators, or blackmail them on side.
 

Deleted member 97083

To be honest, a more successful Maximinus Thrax who didn't hate Gaul might have stopped the problems that brought up this mad-cap idea :p Even if it was just setting up an internal affairs division of the judiciary after his wars in 236. Considering his dislike of the nobility, and his "common man" status, I'm he doesn't seemed to have acted against judicial/legal injustices. It may even have been enough to prevent the year of six Emperors, and could have been a powerful tool to take out corrupt senators, or blackmail them on side.
Well Maximinus Thrax didn't successfully destroy the nobility, fully purge disloyal military officers, nor hate Gaul. I meant an emperor who has the mindset of Maximinus Thrax, but is not him, and is more successful at his aims.

I agree though, many Roman emperors who restricted or heavily taxed the nobility did strengthen the empire.
 
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For me the major loss is the recruitment - if that can be relocated to Britannia, Hispania and Italia
As for what Spain and Italy are concerned, most of the ressources avaible there were almsot entierly used up in local matters already historically. There wasn't much more to take from.
As for Brittania, even disregarding that with Gaul gone, it can't realistically be expected to see anything managing to coming up to whatever remains of the Empire, we're talking of an underdevelloped, under-inhabited and over-militarized part of the Empire already. It's either they take from Britain whatever they can as IOTL, either they let it only to kiss them farewell.

I'll stress this : by the Vth, every place was dried out of reinforcements, and giving the increasing pressure over limes then within Romania itself, it wasn't nearly enough to deal with everything. Giving that Britain was, as far as WRE was concerned, fairly unimportant, it was dried out and leaved to itself waiting for an hypothetical better time. There's no way that the lack of ressources an abandoment of Gaul would be compensated, especially not by an isolated Britain.

I'd be intending to fund it through having fewer fortifications than the Gallic Limes required.
The Gallic limes was fairly already relatively light, compared to Danube, mostly because it was relatively safer.
If something, if we go trough the theoritical organisation of Vth Roman armies, Britain really shows up as having a more militarized (and more or less ineffectual) limes than Gaul. You'd notice as well the absence of significant arsenal in Roman Britain compared to Gaul, which would have meant abandoning not only territory but equipment and military structures.

I can't make it simpler than, militarily, abandoning Gaul in favour of Britain would have meant abandoning both for the sake allowing Barbarians roaming more freely in Romania.
It makes, absolutely, irremediably, entierly, irrevocably, no military or political sense whatsoever.

Do I have the numbers - no, so it would only make sense from a purely fiscal perspective if the savings were large enough
Saving were in Rome, not in the thin network of Britto-Roman cities that didn't managed to protect themselves as one entity when let to their own (pretty much thin themselves) resources. And for what matter paying off the early Vth century Roman army there, it's as we expected (all proportions kept, of course) Afghanistan to pay up for all the expense of Roman army in the country.
I know this is hard to swallow culturally for some people issued from the english-speaking world, but Roman Britain was the less develloped, structured and wealthy of Roman provinces. Period.

Ideally I'd prefer to see my scenario implemented earlier so that the Saxons don't have a power base in Britannia, but that would be down to exactly when this idea would be implemented
It's less about power-bases existing right from the beggining, than laeti and foedi tended to be such after a while and the degradation of Roman authority in the Vth, with leaders generally emerging out of it and mixing up various foedi (but as well provincial) assets. Probably what happened with Cerdic of Wessex which may have been the result of such mixing-up with native leaders going barbarized (if the name of Cerdic is any indication, giving it may be more Brittonic than Germanic).

By the mid-IVth century, in the wake of Pictish/Gaelic/Germanic raids in Britain, you certainly already had a Germanic presence in the Saxon Shores (both side of the Channel).
That said, remember that the ethnogenesis of Barbarian peoples wasn't yet that fixed : most of what ended to be called "Saxon", "Angles" or "Jutes" tended to be a mix of various groups that came at different periods.
For instance, Kentish Jutes may (probably IMO) be a mix of Gaul's, Old Saxony's and Peninsular (possibly on the lead) Jutes driven by the general North Sea moves (themselves driven by Danes and the general disorder in Scandinavia), mixing up with whatever (close enough or not) human groups they went trough, as Frisii.
Generally, Barbarian ethnogenesis involves several waves of settlement and mixng-up with more or less romanized Barbarians or Roman groups, to form a distinct identity after a while.

So even if you manage to nerf Saxons already settled in Britain in the early Vth, they'd likely end up swallowed (or swallowing up as it might have been the case in Wessex) whatever groups add new human layers.

Long story short, it's less about power-bases being already there, than the potential for becoming these (thanks to a military edge) during the collapse of western Roman state.

Implementing a system of fortified towns in the south east and other exposed targets as per Alfred the Great should at least be sufficient
The existing fortifications of the IVth are often considered to have been a disproportioned expense of ressources, tough. Nobody could pay more for this, and by the late IVth, Roman army was already regrouping to the South-East (abandoning the western shores to Gaels, and eventually Hadrian's wall to Picts).
You did have IOTL a re-centering of Roman army in Britain around the south-east. It's just that the historical situations points how it simply wasn't viable.

the only way Britannia could function is with a huge amount of autonomy, with finances and reinforcements sent from Hispania.
But why Rome would have given even more ressources (financial or military) when they didn't have enough already? I'm not picky, I just need one reason why Ravenna would think it would be a good idea to sacrifice the region next-door to your capital that still barely worked out as a military border for the sake of keeping a part of an overly-expensive army in Britain where it would sit all day on their fingers for all the emperor could matter with.

Admitting that they're somehow convinced it's the only right thing to do, regardless of the reason, how could they do so? Classis Britannica and Classis Germanica disappeared by the IIIrd century (probably replaced by a decentralized nvary in the Shore), and you never had that of a noticable naval roman presence in western Spain. How come a WRE that is essentially dependent on ERE to anything remotely tied to seafare could pull an exarchate?

I'm confused, so the Empire can defend the Eastern Alps and the Rhine perfectly fine, but can't fortify/defend the Pyrenees and Western Alps instead?
I strongly advise you to read more carfully posts you're answering.
I specifically said that the Rhine limes was relatively safer, compared to other European limes (especially Danube, but the crumbling limes in Britannia could fairly count) in spite of the events of 407. I also said that eastern Alps were the traditional way of invasion, giving Illyricum was the soft-underbelly, strategically speaking, of Late Romania.

It doesn't mean at the latest "perfectly fine".

Anyway.
No they can't fortify western Alps or Pyrenees, because they had not the ressources to do so : they barely had enough resources (or unity) to not crumble overnight after the death of Honorius, which is why they were more and more reliant over foederati to ensure the security of some regions, as Franks in Toxandria or Saxons in the Channel.
Giving that Barbarians formed more and more of the defensive strategy of the empire (it became painfully obvious with Aetius management of the Catalunic Fields), it would have make no sense attempting (out of an empty treasury) to create new limes against Barbarians if you had to man them with foederati eventually.

I can't make it simpler as : you don't undergo a wide promgram of fortifications while you're being pressured, raided and invaded in all parts of your territory and where you barely manage to pay (when you manage it, which becomes harder each time) your already existing forces, critically in places where it's still failing the lest at its job.

Interestingly the way you describe that just leads me to think that the best Roman solution in the West would always have been to go on the offensive, paying the Foederati with German land
They tried that (notably with Sarmatians peoples; but also germanic peoples such as during Justin's campaigns in Gaul) : it failed to be much of a viable alternative by the IVth with hunnic pressure, climatic change, need for military and rural production manpower,prestige and attraction of core Romania...
It doesn't seems to have been that favoured compared to laeti of the Principate and Dominate, or small-scale foedi eventually.
 
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