Roman Defense of the Zagros?

[EmperorOfTheNorthSea]

Yes this has been talked about a lot in passing but there has only been one thread talking about it so far and it doesn't seem to be as detailed as I (and assuming) others would like.

I have been researching into the nature of the Zagros in many regions and it surprised me how green and wet many parts of it are, and given the drying of the region in modern times I can guess it was even wetter thousands of years ago. Though I continue to try and research it to answer the question of 'can it be defended' it seems that with the material I have been able to find haven't been able to answer that much. So really I'm hesitant to say yes or no without more (and better!) material.

Though From what I have seen it has many mountain valleys that while large enough for Roman formations are too small for parthian cavalry to be as powerful as an offensive force. From what I know I'm guessing that the majority of valleys are too small for any force to move through the area unnoticed.

Anyways, discuss I guess.

Link to other discussion thread (necro'd): https://www.alternatehistory.com/fo...a-from-the-east-fortifying-the-zagros.403355/

 

[SealTheRealDeal]

Yes this has been talked about a lot in passing but there has only been one thread talking about it so far and it doesn't seem to be as detailed as I (and assuming) others would like.

I have been researching into the nature of the Zagros in many regions and it surprised me how green and wet many parts of it are, and given the drying of the region in modern times I can guess it was even wetter thousands of years ago. Though I continue to try and research it to answer the question of 'can it be defended' it seems that with the material I have been able to find haven't been able to answer that much. So really I'm hesitant to say yes or no without more (and better!) material.

Though From what I have seen it has many mountain valleys that while large enough for Roman formations are too small for parthian cavalry to be as powerful as an offensive force. From what I know I'm guessing that the majority of valleys are too small for any force to move through the area unnoticed.

Anyways, discuss I guess.

Link to other discussion thread (necro'd): https://www.alternatehistory.com/fo...a-from-the-east-fortifying-the-zagros.403355/

The mountains themselves are a decent barrier, if the maps I've seen of Persia's Royal Roads is any indication there's only two passes suitable to a high volume of movement. However Rome would need some awkward borders to keep a defensible border as there's a large flat low land in Khuzestan/Bushehr that cuts the mountains off from the coast. There's also the problem that the Zargos mountians share with proposals for Rome holding the Carpathians, they're mountains not rivers. They're much harder to supply and reinforce as they are natural barriers rather than highways.

The Tigris or Euphrates would be much more optimal as it goes right from the Anatolian highlands to the gulf and makes logistics a piece of cake.

 

[RogueTraderEnthusiast]

@SealTheRealDeal - all fair points, especially regarding Bushehr. That'd probably wind up being the main place that the Romans had to fear invasion from, as I don't think they'd hold the region, just the shortest route between the Zagros and the coast. Anything more becomes less and less cost-effective I fear, because the amount of defences needed for a small area of land are higher.

If we exclude Bushehr, we do have a weakness, but not an insurmountable one as the area of land between the Zagros and the coast can be fortified. At which point the Romans have a similar issue for logistics as they did in the Alps, Pyrenees, Atlas Mountains, Anatolian Highlands, Syrian Mountains, etc. All of which were achieved at some point or another, reliably, AFAIK.

So it isn't impossible. It just isn't as pleasant. It might require some logistical innovations, or flat out building new roads and infrastructure to support it - which doesn't have to be a bad thing. As much as the Rhineland benefited from the Roman forts leading to settlements and agricultural trade in the area, you could have the same happen in the Zagros mountains - with mining and trade instead of agriculture.

In fact - that might be how you get the Zagros forts to work - secure places for caravans to resupply. Like Caravanserai.

If you INCLUDE Bushehr, you have a slightly different problem, a distant, expensive to defend region, that could be a linchpin in a defence, but could also be lost. This is a perfect place to send loads of people to settle the region so that it stays loyal (in theory). What it also provides is a region that can provide the Romans great benefits - a strong base for a navy. If Hormuz is Persian/Hostile, having a strong fleet in a well-defended region with a large legion presence means you can literally tear Hormuz off of Persia in a war, and then control trade via Hormuz.

 

[Practical Lobster]

Are there any historic examples of the Zagros being used as a frontier that might inform how we think about this? All I can think is that peoples on the Iranian plateau never seemed to have too much difficulty attacking Mesopotamia at any point in history. If it can be fortified easily, why did nobody think to do so?

 

[RogueTraderEnthusiast]

Are there any historic examples of the Zagros being used as a frontier that might inform how we think about this? All I can think is that peoples on the Iranian plateau never seemed to have too much difficulty attacking Mesopotamia at any point in history. If it can be fortified easily, why did nobody think to do so?

I can't think of anything outside of Modern Iran/Iraq. Off the top of my head most of the time the Empires of the Day were based in Mesopotamia, or on the very edge of it. With the exception of the Parthians and Safavids. (I think).

Perhaps looking at those two would provide an idea?

 

[EmperorOfTheNorthSea]

They're much harder to supply and reinforce

The Romans would (I presume) have the borders only a few miles into the mountains and fortify/guard key mountain passes and valleys, as well as whatever food can be produced in the mountains (usually sheep from nomadic herders but I suppose some areas could grow some crops though probably not enough for a legion). And whatever complications come with supply the tax revenues of Mesopotamia should be more than enough to pay for it.

they are natural barriers rather than highways.

No offense but isn't that the point though?

The Tigris or Euphrates would be much more optimal as it goes right from the Anatolian highlands to the gulf and makes logistics a piece of cake.

I'm not too sure, the Euphrates was good as a border OTL but only just barely and that had only a sliver of Mesopotamia in it.

That and it gets much easier to cross the farther upstream you get so the Area around Armenia would be a dagger pointed at mesopotamia.

Then you have the problem of large cities being on the other side of the river that the enemy can use to station troops and could use to keep up the possibly most reliable supply chain in ancient warfare. River borders are really only good for when bordering barbarian tribes, not so much for large kingdoms and empires hence why OTL when the dacian kingdom was across the danube they still caused a heap of trouble in moesia.

just the shortest route between the Zagros and the coast.

Eh, Hadrian's wall was longer and in a much less productive province. And a single legion with a network of separate auxiliary camps with an efficient network of relays could quite easily be informed of any invading force.

Probably still going to be a weak point in the defense but it should hold up for the most part until the part of Roman history when every successful general and their mothers go out and try to usurp.

It might require some logistical innovations

Perhaps, it may require simply getting local peopl herding large amounts of goats and marching them to a certain destination and butchering them on site. Or perhaps an earlier invention of the wheelbarrow

or flat out building new roads and infrastructure to support it

Kinda what the Romans did wherever they went.

with mining and trade instead of agriculture.

Like I said the Zagros is surprisingly green, while mountains by and large aren't good for agriculture I think they could do more than one would expect.

In fact - that might be how you get the Zagros forts to work - secure places for caravans to resupply. Like Caravanserai.

I could definitely see towns being built outside of Legionary or Auxiliary camps eventually molding and evolving to fit that purpose economically especially when you consider that places for caravansary resupply usually tend to be places with taverns for drinking, gambling, prostitutes, all of which would most undoubtedly come with any permanent military posting.

Are there any historic examples of the Zagros being used as a frontier that might inform how we think about this?

The closest I can think of is the Ottomans but that was in a completely different technological era so I wouldn't say that would count.

If it can be fortified easily, why did nobody think to do so?

Probably because any power based in Mesopotamia has never really had the strength to stand up to an Iranian power and usually just gets crushed easily. The Romans were different because they were a rare example of a power being able to push an Iranian power back.

Also because the point in history it would have been possible or necessary would have only been for about three thousand years and you can only have so many states and polities in such a short span of time. And for when the most part when Mesopotamia is under an Iranian power there will be no incentive for an Iranian power to fortify the zagros so we only have the short period of times when Mesopotamia isn't under an Iranian power which is only a very few times in history.

 

[calvin1417]

The mountains themselves are a decent barrier, if the maps I've seen of Persia's Royal Roads is any indication there's only two passes suitable to a high volume of movement. However Rome would need some awkward borders to keep a defensible border as there's a large flat low land in Khuzestan/Bushehr that cuts the mountains off from the coast. There's also the problem that the Zargos mountians share with proposals for Rome holding the Carpathians, they're mountains not rivers. They're much harder to supply and reinforce as they are natural barriers rather than highways.

The Tigris or Euphrates would be much more optimal as it goes right from the Anatolian highlands to the gulf and makes logistics a piece of cake.

A river border is easy to supply but how defenseable is it compared to mountains? Sure borders must be supplied but it can't be at the complete expense of defense

 

[Earth Judicar]

Could they have fortified the mountain passes?

 

[SealTheRealDeal]

The Romans would (I presume) have the borders only a few miles into the mountains and fortify/guard key mountain passes and valleys, as well as whatever food can be produced in the mountains (usually sheep from nomadic herders but I suppose some areas could grow some crops though probably not enough for a legion). And whatever complications come with supply the tax revenues of Mesopotamia should be more than enough to pay for it.

The Zagros could certainly support Limitanei forts, but I'd be very skeptical of their ability to support proper Roman field armies, which is what actually would be needed should the Parthian/Sassanian Royal Army tried to force a crossing. Should that happen the Roman legions reinforcing the border would quite literally have to face an uphill battle.

No offense but isn't that the point though?

Um really no. You'd be a pretty good candidate for a darwin award if you tried to cross a highway on foot. Similarly rivers are difficult to cross, even in for modern day militaries they can be some of the most dangerous terrain to encounter. However they are very easy to travel along, which makes patrolling, and sending field armies to repel invaders much more easy.

Mountains are just as hard (or possibly even harder) to travel along as they are to travel across.

I'm not too sure, the Euphrates was good as a border OTL but only just barely and that had only a sliver of Mesopotamia in it.

I did mention that the Tigris is also an option, and that would give the lion's share of Mesopotamia.

That and it gets much easier to cross the farther upstream you get so the Area around Armenia would be a dagger pointed at mesopotamia.

With the border that the Romans settled on IOTL it was a dagger pointed directly at Syria, and with the border you propose it would still pose a threat to Mesopotamia. Short of conquering the Iranian plateau this region is going to be a geographic gap, and the Romans seemed willing to accept that IOTL.

Then you have the problem of large cities being on the other side of the river that the enemy can use to station troops and could use to keep up the possibly most reliable supply chain in ancient warfare. River borders are really only good for when bordering barbarian tribes, not so much for large kingdoms and empires hence why OTL when the dacian kingdom was across the danube they still caused a heap of trouble in moesia.

The same goes for mountains too, and Mesopotamia is far from being Persia's only urbanized region.

we only have the short period of times when Mesopotamia isn't under an Iranian power which is only a very few times in history.

Wat? Did the Bronze Age and ever age after the iron age not happen?

 

[SealTheRealDeal]

A river border is easy to supply but how defenseable is it compared to mountains? Sure borders must be supplied but it can't be at the complete expense of defense

Given that Rome's Danube and Rhine frontiers held for centuries, I'd say that they're quite defendable. Also in addition to facilitating troop movements, they could also allow prefabricated scorpions and larger ballistas to be quickly moved via boat which could then act as weapons platforms on arrival.

 

[RogueTraderEnthusiast]

Wat? Did the Bronze Age and ever age after the iron age not happen?

.... fair point. Do we have any examples of note to draw from there?

 

[EmperorOfTheNorthSea]

A river border is easy to supply but how defenseable is it compared to mountains?

Really only defensible when the enemy is a backwater tribe, as seen with the whole reason the Dacian Kingdom was conquered because they were constantly launching raids into Roman Moesia.

Could they have fortified the mountain passes?

Thats what I've been advocating for the most part. Or just straight up building walls and gates along the medium sized ones and full on legionary camps and towns along the big ones.

Parthian/Sassanian Royal Army tried to force a crossing. Should that happen the Roman legions reinforcing the border would quite literally have to face an uphill battle.

With the usual Parthian/Sassanian reliance on their cavalry a closed battle in a mountain pass can only favor the infantry based Romans. And when it came to infantry battles the Romans nearly always win.

That and if they're fighting from a fortified position they should be the ones with a high ground as well as pre-placed artillery such as Scorpio, Ballistae,and early catapults meaning that the enemy would have to have a clever way of attacking.

You'd be a pretty good candidate for a darwin award if you tried to cross a highway on foot.

Yes but if you want people to not cross then a barrier is exactly what you're looking for.

However they are very easy to travel along, which makes patrolling, and sending field armies to repel invaders much more easy.

Yes but it's also far more easy for an enemy to choose an unpredictable spot to cross rather than having to choose to cross a handful of most likely fortified mountain passes.

Mountains are just as hard (or possibly even harder) to travel along as they are to travel across.

You don't need to travel across them, just mountain passes and valleys. It is literally impossible for an army to cross a mountain otherwise, spies perhaps but you're not going to be able to stop them anyways unless you have a 21st century Korean DMZ at you're disposal.

I did mention that the Tigris is also an option, and that would give the lion's share of Mesopotamia.

Maybe, but there would still be plenty of issues that would have to be addressed.

With the border that the Romans settled on IOTL it was a dagger pointed directly at Syria, and with the border you propose it would still pose a threat to Mesopotamia. Short of conquering the Iranian plateau this region is going to be a geographic gap, and the Romans seemed willing to accept that IOTL.

True enough I suppose.

The same goes for mountains too, and Mesopotamia is far from being Persia's only urbanized region.

Yes but there are no large cities or towns on the other side of the eastern zagros, the closest one would be Susa and given its going to be near that gap that people have been mentioning earlier I would say there would an emphasis on that region in the defense budget.

Wat? Did the Bronze Age and ever age after the iron age not happen?

Fair enough, I should have said after the Iranian plateau had actually begun to Urbanize and develop until they could afford to mass armies and form states. But when you take that into account from then to the age of Firearms the Mesopotamian region has usually been under the influence of an Iranian based power with short blips here and again and almost never independent(i.e. under Rome, Arabia, ect) with the largest being under the Caliphates I believe.

Given that Rome's Danube and Rhine frontiers held for centuries, I'd say that they're quite defendable.

They're defendable against poor backwater tribes who have more to loose than gain from fighting(kind of when the Migration period happened the Rivers didn't stop tribes from crossing though the civil wars and such probably didn't help with that) and serves mostly as an arbitrary line only to serve to slow down any invading force long enough to catch up to and defeat.

Against an organized kingdom or Empire using a river border does not work as well, OTL the whole reason for the conquest of Dacia was because they kept crossing the Danube and raiding Moesia.

they could also allow prefabricated scorpions and larger ballistas to be quickly moved via boat which could then act as weapons platforms on arrival.

Maybe. But in the Mountain passes you could have those right exactly where the enemy will be coming from.

.... fair point. Do we have any examples of note to draw from there?

The closest I can think of is the Assyrian empire.

 

[SealTheRealDeal]

.... fair point. Do we have any examples of note to draw from there?

Babylon and Elam comes to mind, and Elam sacked Babylon twice IIRC, so that doesn't bode too well for the Zagros frontier.

With the usual Parthian/Sassanian reliance on their cavalry a closed battle in a mountain pass can only favor the infantry based Romans. And when it came to infantry battles the Romans nearly always win.

A proper army sure, Limitanei are getting crushed.

Yes but if you want people to not cross then a barrier is exactly what you're looking for.

And a river is a fine barrier to people trying to cross it.

Yes but it's also far more easy for an enemy to choose an unpredictable spot to cross rather than having to choose to cross a handful of most likely fortified mountain passes.

It's really not, for a large army to cross it would need a considerable build up of boats over a long period of time, which due to the ease of patrolling the river would easily be noticed.

Yes but there are no large cities or towns on the other side of the eastern zagros, the closest one would be Susa and given its going to be near that gap that people have been mentioning earlier I would say there would an emphasis on that region in the defense budget.

Khorramabad and Hamadan are also pretty near the mountainous frontier, and Taurus would be basically right beside the Armenian gap. I reiterate, the pre-mongol Iranian Plateau really should not be underestimated.

They're defendable against poor backwater tribes who have more to loose than gain from fighting(kind of when the Migration period happened the Rivers didn't stop tribes from crossing though the civil wars and such probably didn't help with that) and serves mostly as an arbitrary line only to serve to slow down any invading force long enough to catch up to and defeat.

That's really not true in the slightest, and it's not like the Alps proved much better when the empire was weakened.

Against an organized kingdom or Empire using a river border does not work as well,

It actually works better because it's disrupting a complex logistical system rather than just making the armed refugees gather up some rowboats.

OTL the whole reason for the conquest of Dacia was because they kept crossing the Danube and raiding Moesia.

The Dacian raids across the Danube occurred when Rome was still recovering from the Year of Four Emperors, its military was over stretched, and most of the limes were not yet established.

Maybe. But in the Mountain passes you could have those right exactly where the enemy will be coming from.

Maybe? They used such tactics on the Danube I fail to see why they would not in Mesopotamia.

But when you take that into account from then to the age of Firearms the Mesopotamian region has usually been under the influence of an Iranian based power with short blips here and again and almost never independent(i.e. under Rome, Arabia, ect) with the largest being under the Caliphates I believe.

I'd be unsure of that, there's the Seleucid empire, the early iron age, and basically the entire Islamic period to factor in.

 

[EmperorOfTheNorthSea]

Babylon and Elam comes to mind, and Elam sacked Babylon twice IIRC, so that doesn't bode too well for the Zagros frontier.

True but Babylon didn't have the Manpower or Militaristic culture the Romans had. I don't even really know if they bordered the Zagros or made any attempt to fortify it.

A proper army sure, Limitanei are getting crushed.

Eh, Limitanei were only organized after the Crisis of the Third century. In an ATL they might not ever exist. But for a border with a handful of restricted paths of movement it's not unreasonable to assume they could afford to Garrison enough troops or at the very least scouts that could report the enemy's position and hold them off long enough for reinforcement.

And a river is a fine barrier to people trying to cross it.

Somewhat. Individual traders and merchants aren't going to be stopped by rivers (quite the opposite) and while Large armies will be slowed by Rivers small scouting detachments have been able to cross rivers sometimes in mid-battle.

Besides its possible to swim across a River with some preparation, its a lot harder to cross a mountain.

for a large army to cross it would need a considerable build up of boats over a long period of time

Thats why they would send small detachments to raid and harry the enemy's supply line and such. dozens Forces as small as fifteen men could be sent to divert away attention.

Besides building rafts can be easily concealed.

Khorramabad and Hamadan

Ecbatana and Khaydalu (the ancient names of those places) where somewhat close to the Zagros but not within literal stone's throw of a range.

That's really not true in the slightest, and it's not like the Alps proved much better when the empire was weakened.

Isn't that because invading tribes just went around them? I suppose the same can be said for the Zagros but circumnavigating the Zagros would be quite the lengthy journey.

I mean the Alps are pretty defensible, the only reason Hannibal could cross was because ingenious use of tools and the fact Romans didn't expect him to actually try crossing it.

The Dacian raids across the Danube occurred when Rome was still recovering from the Year of Four Emperors, its military was over stretched, and most of the limes were not yet established.

True the Dacians did take advantage of the Year of four Emperors but king Decebalus did manage to defeat Domitian in battle several times and raid Moesia while doing so.

Maybe? They used such tactics on the Danube I fail to see why they would not in Mesopotamia.

They could, and the Danube did have a lot more waterfalls and cataracts than the Tigris or Euphrates did. But letting the enemy have encampments across the River would still be dangerous from their pre-placed artillery (Catapult and Ballistae, though the Parthians didn't have much of either of these though they could adapt) alone. Though that would be an interesting scene for a Roman Army fighting another Army but not being able to engage directly and just fling artillery at eachother.

I'd be unsure of that, there's the Seleucid empire, the early iron age, and basically the entire Islamic period to factor in.

And? I said it was mostly under an Iranian power or Influence with when it wasn't was either in very rare(and short) times or under another outside power. At least past the Early Iron age when the Iranian plateau was more than few sputtering mass of villages and cities.

 

[SealTheRealDeal]

Somewhat. Individual traders and merchants aren't going to be stopped by rivers (quite the opposite) and while Large armies will be slowed by Rivers small scouting detachments have been able to cross rivers sometimes in mid-battle.

Besides its possible to swim across a River with some preparation, its a lot harder to cross a mountain.

Scouting detachments aren't going to sack Babylon and drive the Romans back to Syria. And I'll point out that no one is swiming across the Tigris or Euphrates without discarding their weapons and armour.

Besides building rafts can be easily concealed.

You seem to be underestimating the number and size of the rafts that would be needed for the Parthian royal army, especially given the humber of horses that would need to be ferried over.

And? I said it was mostly under an Iranian power or Influence with when it wasn't was either in very rare(and short) times or under another outside power. At least past the Early Iron age when the Iranian plateau was more than few sputtering mass of villages and cities.

Ok, so if we hold 678BC (start of the Median Empire) as the point when Iran became a serious player (although an argument could be made for Elam), and 1473AD (Battle of Otlukbeli) as when gunpowder became the deciding military factor in the middle east then we get a period of 2151 years to examine. Durring that time Mesopotamia was ruled by the Achaemenids for 208 years, the Parthians for 363 years, the Sassanids for 427 years, the Buyids for 110 years, and the very persianate Seljuks for 101 years for a total of 1209 years. Meaning that Mesopotamia was ruled by Iranians for 56.2% of the specified time. So while mostly dominated by the Iranian Plateau, there's also a lot of examples of that not being the case, although it's independence is indeed very rare.

 

[calvin1417]

The Zagros could certainly support Limitanei forts, but I'd be very skeptical of their ability to support proper Roman field armies, which is what actually would be needed should the Parthian/Sassanian Royal Army tried to force a crossing. Should that happen the Roman legions reinforcing the border would quite literally have to face an uphill battle.


Um really no. You'd be a pretty good candidate for a darwin award if you tried to cross a highway on foot. Similarly rivers are difficult to cross, even in for modern day militaries they can be some of the most dangerous terrain to encounter. However they are very easy to travel along, which makes patrolling, and sending field armies to repel invaders much more easy.

Mountains are just as hard (or possibly even harder) to travel along as they are to travel across.


I did mention that the Tigris is also an option, and that would give the lion's share of Mesopotamia.


With the border that the Romans settled on IOTL it was a dagger pointed directly at Syria, and with the border you propose it would still pose a threat to Mesopotamia. Short of conquering the Iranian plateau this region is going to be a geographic gap, and the Romans seemed willing to accept that IOTL.


The same goes for mountains too, and Mesopotamia is far from being Persia's only urbanized region.


Wat? Did the Bronze Age and ever age after the iron age not happen?

Limitanei? The only time the Roman could conquer and hold Mesopotamia is during the princapet. By the time limitanei units really became a thing it was too late.

Given that Rome's Danube and Rhine frontiers held for centuries, I'd say that they're quite defendable. Also in addition to facilitating troop movements, they could also allow prefabricated scorpions and larger ballistas to be quickly moved via boat which could then act as weapons platforms on arrival.

yeah with huge armies manning the forts. When they armies are gone or reduced though the Germans tend to easily invade. That’s why the Germans had such an easy time entering the empire during the fall of the west. A better border needs less men to protect so could actually hold when the enivtable civil war comes and most of the men are off to fight to make there general emperor or something

 

[SealTheRealDeal]

Limitanei? The only time the Roman could conquer and hold Mesopotamia is during the princapet. By the time limitanei units really became a thing it was too late.

Did the Romans of the Principate have a term for 'border guards"? I was just using the term to communicate the idea of border troops rather than field armies.

yeah with huge armies manning the forts. When they armies are gone or reduced though the Germans tend to easily invade. That’s why the Germans had such an easy time entering the empire during the fall of the west. A better border needs less men to protect so could actually hold when the enivtable civil war comes and most of the men are off to fight to make there general emperor or something

The same really goes for mountains. The forces guarding the pass are missing or insufficient than the pass is effectively open. There's no such thing as a border that doesn't need guards.

 

[Deleted member 97083]

Are there any historic examples of the Zagros being used as a frontier that might inform how we think about this? All I can think is that peoples on the Iranian plateau never seemed to have too much difficulty attacking Mesopotamia at any point in history. If it can be fortified easily, why did nobody think to do so?

Ur-III, the Neo-Assyrian Empire, and the Neo-Babylonian Empire all had Zagros as a frontier, as did the Abbasid Caliphate in its later years.

 

[calvin1417]

Did the Romans of the Principate have a term for 'border guards"? I was just using the term to communicate the idea of border troops rather than field armies.


The same really goes for mountains. The forces guarding the pass are missing or insufficient than the pass is effectively open. There's no such thing as a border that doesn't need guards.

Yeah but mountains need less guards so they can be maintained more was when the inevitable round of civil wars happen

 

[SealTheRealDeal]

Yeah but mountains need less guards so they can be maintained more was when the inevitable round of civil wars happen

You misjudge the ferocity of Roman civil wars. The Limitanei were specifically formed to prevent political implosions from stripping the borders.