Could the Persian Empire logistically support an army several million strong?

[Patrick Waterson]

I'd be in danger of breaking the 1000 repeats rule   Put simply, I put a much greater weight on the problems of logistics, particularly issues like "over the beach" supply with small ships, the small buffer that a maximum one week supply baggage train gives when operating at the end of a long nautical supply chain, the capacity of that supply chain to actually deliver given the technology and the variable weather, the viability of marching in dense blocks nose to tail for 15km a day through basically unprepared ground churned up and defecated on, whether they really could find fuel for and prepare food for that large a number, water management, feeding the animals and keeping them fit.  There are other issues around failure to look at sources critically and the perspective of other examples in military history.  Is that enough?

I shall watch for fascinating explanations along these lines of why Mogul armies were unable to operate in India.

Before looking at Anthony's reservations, let us examine Xerxes' Hellespont crossing.  The 'bridges' were triremes and pentekonters laid side to side with a roadway laid over them (it would realy help if people who want to discuss the matter actually read the source beforehand).  A trireme was about 120 feet long, a pentekonter not much less.  Of this, I estimate about 100 feet would be usable as roadway width, given the erection of a hoarding on each side of the road to avoid the animals being spooked by the unfamiliar sight of water everywhere.

100 feet of width allows about 16 men to cross abreast, assuming 6' per man.  This may be an over-generous estimate, but it gives us a useful minimum for the number of men who can cross abreast.

Allow the column to move at 1.5 mph - half normal walking speed - to allow for gaps between units and an element of 'hurry up and wait'.  Herodotus notes the army crossed continually day and night 'under the lash', which indicates measures having been taken to expedite travel.  1.5 mph may thus be a conservative estimate.

Given 6' depth per man on the march, 1,320 men x 16 abreast would pass a given point each hour, or 21,220 men.  Say 20,00 because the Achamenids were fond of blocks of 10,000 men.

In 24 hours, 24x20,000 or 480,000 men, close to half a million, will have crossed.

The entire army of 1.7 million could thus be across in four days and nights.  Herodotus has the crossing take seven days and nights.  The Hellespont bridge starts to look like a very effective crossing whose potential was not fully exploited, in that in the time available another 1.3 million men could have crossed.  In practice, the difference might be ascribable to making special preparations to lead across cavalry and chariot horses and periodically maintaining the earth-and-branches-over-timber crossing surface.


Now let us consider Anthony's other concerns.

Food and water.
As Anthony points out, managing huge quantities of resources requires specialist skills.  I would suggest that as the Achaemenid Empire existed at the terminus of an era in which according to al our primary sources huge armies were the norm and are recorded as campaigning sometimes for considerable distances, often through very unpromising terrain (e.g. Assyrian campaings against Urartu), that such skills not only existed but were part and parcel of Achamenid repertoire.

The biggest challenge would be watering enormous numbers of baggage animals at the end of each day.  From earlier posts, it seems some people envisage a mad scramble by herds of bellowing creatures down riverbanks and into muddy water, perhaps dropping digestive products on the way.  But why do things the hard way when the animals can be lined up and channels dug from the water source to the animals, an arrangement which also makes the animals easier to feed and incidentally leaves relatively tidy rows of fertiliser behind for the local farmers once the army leaves?

How matters are organised is a very important consideration.  If men are camped along a river in depth and channels dug (in advance by pioneer forces if need be) for them, water distribution is much more efficient and hygienic than if everyone rushes to the river and stomps around filling their waterskins.  By in effect creating a miniature hydraulic distribution system at every halt one can handle available water supplies much more efficiently than by leaving it to the men to sort themselves out.  But how many studies have examined this aspect?  As far as I know, none.

Fuel
Probably the least of the challenges.  Manpower for woodcutting parties would be abundant, and northern Greece was fairly well wooded.  Making sure the wood went where it was wanted when it was wanted would be the main concern, one readily obviated by having the woodcutters mainly work ahead of the army.  The humans prepare their own food; the animals have theirs distributed, which probably involves the major work effort of the day.  At least food for animals does not need to be cooked; humans cook their own food.

Supply chain
The major gripe here, judging by past coversations, would seem to be unloading over the beaches.  I do not see this as a major difficulty except in inclement weather, in which event everything would come to a halt and the shipping would be endangered (as indeed happened).  The Mediterranean is effectively tideless, which means a daylight-wide unloading 'window' as opposed to the few hours around high tide customary elsewhere.  Mediterranean shipping, as used by the Achaemenids, was optimised for conditions, including unloading, in the Mediterranean.  Hence their unloading (and loading) capacity was probably much higher then we envisage.

Having unloaded a ship, the resultant supplies are of little use unless picked up and distributed by a beach and land supply organisation.  The principal emphasis here would be on restocking the baggage train, swifter and more efficient than attempting to distribute supplies directly to troops.  Those concerned would have done this sort of thing before, or would be instructed by those who had.

The basic point about the Achaemenid system is that if they were doing these things, as seems likely, then examples from other periods in history can be at the very least misleading, e.g. beach unloading figures for World War 2 in Normandy and the Pacific are not comparable because of tides, enemy opposition, 'combat loading' of ships and inadequate measures for ship-to-shore transfer.

Sources
All too easily nowadays sources are treated as optional extras (except when they are held to prove a point, at which point the most obscure reference is seized upon as certain).  Instead of adopting the idee fixe that I think this therefore the source must be wrong, give the source a chance.  Yes, the Achamenids did have problems - eventualy terminal - maintaining Xerxes' army.  This in itself points to the army's extraordinary size, given the shipping resurces allocated to its support.

There is also Anthony's doubt that a large number of anything could be properly organised.  Now it is not a complete answer to say that such numbers (of ships) would not have been brought along if they could not have been used effectively, because history is replete with large numbers of ineffectives appearing on battlefields, and an exemplar of this is the Achaemenid army.  I would however point out that the Achaemenid Empire, like its predecessors, was highly organised and heavily bureaucratic, and if anyone could organise such numbers for effective use, they could.

[Patrick Waterson]

Storing grain for the rest of the year to the next harvest was possible with a little care.
The problem is people talking of stockpiling it for several years. That is an entirely different issue

Well, someone must have managed it.  When Jacob's family dropped into Egypt to stock up on grain, they were issued stocks which had been around for a number of years.

[Mark G]

I mis spoke.

Some of this is beyond irony.

[Patrick Waterson]

If you have a point to make, Mark, please make it.

[Duncan Head]

We can leave it at that if you wish. The numbers tell me that the logistical capacity was theoretically more than enough to support such an army. I would accept it was not enough only if some demonstrable causes impeding its operation could be proven to exist. The leeway for friction is certainly there: theoretically 800 ships were enough to get one kilogram of grain per day to each man, and Xerxes had 3000 ships.

You mean that Xerxes is said to have had 3,000 ships by the very same source that says he had 3,000,000 men, surely? What independent evidence do we have on the shipping capacity of the eastern Mediterranean?

[Jim Webster]

Storing grain for the rest of the year to the next harvest was possible with a little care.
The problem is people talking of stockpiling it for several years. That is an entirely different issue

Well, someone must have managed it.  When Jacob's family dropped into Egypt to stock up on grain, they were issued stocks which had been around for a number of years.

It is, quite literally, simple maths that anybody who has ever worked a grain store can cope with.
We have 7 year surplus, let's assume 10%

So each year you eat 100 tons.
In year 1 you eat 100 tons, but have 10 left over.
In year 2, you eat 100 tons, including the 10 left over, so have 20 left over (all from year 2)
In year 3, you eat 100 tons, including the 20 left over, so have 30 left over
In year 4, you eat 100 tons, including the 30 left over, so have 40 left over
in year 5 you eat 100 tons, including the 40 left over, so have 50 left over
In year 6 you eat 100 tons, including the 50 left over, so have 60 left over
in year 7 you eat 100 tons, including the 60 left over, so have 70 left over.

Then you get the years of famine. Note that by this point you have no grain in your grain store more than 1 year old. But in the year of famine you harvest only 90 tons
So in year 1 you eat 100 tons, 70 of it from store, so have 60 left in store
in year 2 you eat 100 tons, 60 from store, so have 50 left in store
in year 3 you eat 100 tons, 50 from store, so have 40 left in store
in year 4 you eat 100 tons, 40 from store, so have 30 left in store
in year 5 you eat 100 tons, 30 from store, so have 20 left in store
in year 6 you eat 100 tons, 20 from store so have 10 left in store
in year 7 you eat 100 tons, 10 from store so the store is now empty

That is how grain storage works. You can carry your people through seven years bounty and seven years famine, but never once do you have grain more than a year old in your grain store.
There is no evidence anybody was issued stocks that had been around a number of years. Firstly you don't do it because it rots and gathers vermin, second you don't do it because a properly managed grain store doesn't need to do it

[Justin Swanton]

Thus far the main potential obstacles brought forward are:

You decided to ignore mine then ?

I'll look at yours in more detail, promise (going to bed now). In the meantime here is a pdf with a series of Google Maps images of the most likely route for the Persian army from the Dardanelles to Greece. The scale of each image is in the bottom right corner - I close in for a few screenshots to have a better look at difficult terrain. I see a couple of rough patches but no real chokepoints that would oblige everyone to pass through a narrow defile only a couple of dozen yards wide. Let me know what you think.

[Dangun]

Thus far the main potential obstacles brought forward are:

There are more...

Limitations of the land available to accommodate camp area
Not just the availability of water, but its capture
Practical limits to total camp area
Not just the availability of water but distribution post capture
Bottlenecks
Maximum length of march without resupply
Animals checking up hill
Spacial problems of column length - not just width

I understand the desire to rely on literary histories, but... what is being posited has never since been achieved in the history of warfare.

[Justin Swanton]

We can leave it at that if you wish. The numbers tell me that the logistical capacity was theoretically more than enough to support such an army. I would accept it was not enough only if some demonstrable causes impeding its operation could be proven to exist. The leeway for friction is certainly there: theoretically 800 ships were enough to get one kilogram of grain per day to each man, and Xerxes had 3000 ships.

You mean that Xerxes is said to have had 3,000 ships by the very same source that says he had 3,000,000 men, surely? What independent evidence do we have on the shipping capacity of the eastern Mediterranean?

One approach is to look at the scale of Mediterranean shipping during the Roman Empire. Rome needed 420 000 tonnes of grain brought by ship each year. If the average Roman merchant ship had a carrying capacity of 100 tons that means 4200 ship voyages to feed the city. But I don't know how many voyages each ship would make per year. This excludes other foods and goods brought to Rome and of course all commercial shipping to other cities around the Mediterranean littoral.

If we discount the figures given and choose, say 200 000 men plus 200 000 support personnel, then what do we make of the bridges over the Hellespont? Divide 200 000 by 7 days then 24 hours and 1190 men passed by any given point of the bridge each hour. Supposing the men moved in a column 20 men wide that means that a block of men 20 wide and 60 deep took an hour to cross that point. This would clearly make the seven days and seven nights a fabrication as one day would be enough to get the entire army across. I suppose one could discount the entire bridge account and assume the troops were ferried across. But once we've discounted this much, what can we then believe?

[Justin Swanton]

Thus far the main potential obstacles brought forward are:

There are more...

Limitations of the land available to accommodate camp area
Not just the availability of water, but its capture
Practical limits to total camp area
Not just the availability of water but distribution post capture
Bottlenecks
Maximum length of march without resupply
Animals checking up hill
Spacial problems of column length - not just width

I understand the desire to rely on literary histories, but... what is being posited has never since been achieved in the history of warfare.

How big would the camp be? This estimate of the numbers of men in Roman camps in Britain has an upper figure of 1189 men per hectare. That's 8.4 square metres per man, which leaves space for pack animals. 3 400 000 men using this yardstick gives you a camp of 2860 hectares, or 5,4 x 5,4 km. Supposing a river runs through the middle of the camp, it would take half an hour at the most to reach it from any point in the camp. If the camp were long and narrow, following the course of the river, one would reach it in much less time.

A camp arranged in a rough half-circle along the coast would occupy 8.5km of coastline and have a maximum depth of 4,3km. This is all just suggestive but does give an idea of the scales involved.

What would make a 3 1/2 million man army impossible would be chokepoints that forced all the men and animals to file through a narrow space without being able to pass over the higher ground on either side. I can't a priori see any such chokepoints from my Google Maps tour but of course Google Maps isn't the same as being on the spot. Has anyone identified such chokepoints?

Sure, in the history of warfare since Persia such an exercise has not been achieved because it hasn't been attempted. The Greeks proved you don't need huge armies to win battles, and once Alexander hammered the lesson home quality took the place of quantity from then on.

As an exercise (and then I'm really leaving it at that) here is a proposed route for the Persian march, on the assumption that the army does about 20km a day and its camps measure about 6x6km. It seems doable.







Erratum: That alternative inland route in map 2 wouldn't work as it would take too many days to complete before reaching the sea again...I think.

[Jim Webster]

How big would the camp be? This estimate of the numbers of men in Roman camps in Britain has an upper figure of 1189 men per hectare. That's 8.4 square metres per man, which leaves space for pack animals. 3 400 000 men using this yardstick gives you a camp of 2860 hectares, or 5,4 x 5,4 km. Supposing a river runs through the middle of the camp, it would take half an hour at the most to reach it from any point in the camp. If the camp were long and narrow, following the course of the river, one would reach it in much less time.

What would make a 3 1/2 million man army impossible would be chokepoints that forced all the men and animals to file through a narrow space without being able to pass over the higher ground on either side. I can't a priori see any such chokepoints from my Google Maps tour but of course Google Maps isn't the same as being on the spot. Has anyone identified such chokepoints?

Sure, in the history of warfare since Persia such an exercise has not been achieved because it hasn't been attempted. The Greeks proved you don't need huge armies to win battles, and once Alexander hammered the lesson home quality took the place of quantity from then on.

Firstly the Romans set a uniquely high standard for their camps, we know that from comments by people like Pyrrhus. By the time we get to the camps in Britain they were a professional army with several centuries of experience at building them. The idea that over three million Persian baggage personnel would keep to Roman levels of efficiency is a very large assumption indeed. We know of nobody else in this period who did, certainly not the Greeks.

But even with your super efficient camp pitching Persian army. If, as you say, they could make it long and thin to ensure that everybody was within a sensible distance of water (and with every contingent's baggage animals kept together at the downstream end) and this just meant the camp was 10.8km long
If they left the camp by the narrow end, that means that for some troops, over six miles of their daily march would be through the camp

[Patrick Waterson]

Firstly the Romans set a uniquely high standard for their camps, we know that from comments by people like Pyrrhus. By the time we get to the camps in Britain they were a professional army with several centuries of experience at building them. The idea that over three million Persian baggage personnel would keep to Roman levels of efficiency is a very large assumption indeed. We know of nobody else in this period who did, certainly not the Greeks.

One point to remember about Roman camps was their habit of leaving a belt of a couple of hundred yards around the perimeter unoccupied to prevent casualties from incoming enemy missiles.  So in terms of efficiency of packing men into the available space they actually come out comparatively poorly and it is a fairly safe bet that practically anyone else with long experience of creating military encampments (the Achaemenids inherited what the Medes had learned from the Assyrians) would do better simply by forgoing this missile buffer zone.

But even with your super efficient camp pitching Persian army. If, as you say, they could make it long and thin to ensure that everybody was within a sensible distance of water (and with every contingent's baggage animals kept together at the downstream end) and this just meant the camp was 10.8km long
If they left the camp by the narrow end, that means that for some troops, over six miles of their daily march would be through the camp

And why leave the camp 'by the narrow end'?  Why not leave it by contingents all along its length, just as they arrived?

On grain storage

But in the year of famine you harvest only 90 tons

This only works if your famine level of production is quite close to your abundance level of production.  I appreciate the thinking, but if your abundance level is 150 tons and your famine level 50 tons then after a couple of years of the famine this approach is dead and so is half your population.

I think we have to face the possibility that Biblical and classical cultures could store grain better than we can.  And I suspect the difference lies in the use of sealed amphorae for transport and various chemical methods of preservation.

"The ancient Egyptians first believed that supernatural powers can control pest species including insects, mice and rats, however subsequently they employed for this purpose washing by soda solution, application of animal fat and dung ash (papyrus Ebers, ˜1600 B. C.) as well as sulphur dust and sulphur dioxide (during the New Kingdom)." - source

You mean that Xerxes is said to have had 3,000 ships by the very same source that says he had 3,000,000 men, surely? What independent evidence do we have on the shipping capacity of the eastern Mediterranean?

I think the question should be: what independent evidence do we have to justify any other conclusion?  Otherwise we are just source-bashing for source-bashing's sake.

[Jim Webster]

Firstly the Romans set a uniquely high standard for their camps, we know that from comments by people like Pyrrhus. By the time we get to the camps in Britain they were a professional army with several centuries of experience at building them. The idea that over three million Persian baggage personnel would keep to Roman levels of efficiency is a very large assumption indeed. We know of nobody else in this period who did, certainly not the Greeks.

One point to remember about Roman camps was their habit of leaving a belt of a couple of hundred yards around the perimeter unoccupied to prevent casualties from incoming enemy missiles.  So in terms of efficiency of packing men into the available space they actually come out comparatively poorly and it is a fairly safe bet that practically anyone else with long experience of creating military encampments (the Achaemenids inherited what the Medes had learned from the Assyrians) would do better simply by forgoing this missile buffer zone.

right, so now we have the Achaemenids who are so slick and efficient we have them packing pack camels and porters more tightly and efficiently that the Romans could do with professional soldiers
All that happens when you pack troops more tightly is that it makes it awfully difficult to move about the camp or to leave it.
Anyway these fabulous Achaemenid camps? Is there any evidence for them? Any signs of them on the ground? What did Xenophon say about them in his Cyropedia, or his Anabasis because, after all, he lived in Persian camps for a spell. If they were miracles of order and densely packed humanity under Xerxes, how much better must they have been in Xenophon's day?

So it looks as if the super dense Achaemenid camp is another construct produced on no evidence which is necessary to allow armies the like of which have never been seen before or since to exist

[Jim Webster]

But even with your super efficient camp pitching Persian army. If, as you say, they could make it long and thin to ensure that everybody was within a sensible distance of water (and with every contingent's baggage animals kept together at the downstream end) and this just meant the camp was 10.8km long
If they left the camp by the narrow end, that means that for some troops, over six miles of their daily march would be through the camp

And why leave the camp 'by the narrow end'?  Why not leave it by contingents all along its length, just as they arrived?

Because Justin had it long and narrow to allow the army to have access to water. If you leave it all along its length then at least half the army is going to have to cross the river.
(Yes, I realise that half the army would have had to cross the river the previous evening with the obvious effects on drinking quality but I drew a veil over that, preferring to assume that the army was marching along the river, with half on either bank)

[Jim Webster]

On grain storage

But in the year of famine you harvest only 90 tons

This only works if your famine level of production is quite close to your abundance level of production.  I appreciate the thinking, but if your abundance level is 150 tons and your famine level 50 tons then after a couple of years of the famine this approach is dead and so is half your population.

I think we have to face the possibility that Biblical and classical cultures could store grain better than we can.  And I suspect the difference lies in the use of sealed amphorae for transport and various chemical methods of preservation.

"The ancient Egyptians first believed that supernatural powers can control pest species including insects, mice and rats, however subsequently they employed for this purpose washing by soda solution, application of animal fat and dung ash (papyrus Ebers, ˜1600 B. C.) as well as sulphur dust and sulphur dioxide (during the New Kingdom)." - source

I read the sources, it was a document I referred you to
Firstly please show me a country where people live a settled existence where they have that level of difference between famine and abundance? Inventing fantasy examples does not invalidate reality
Secondly, of course with settled agriculture your famine level is close to your abundance level. Areas which have settled agriculture tend to have a population which can be supported under normal circumstances.
But with agriculture, put the same crop in the same field with the same inputs in two consecutive years and there can be 10% difference in the yield, even now.

As for "I suspect the difference lies in the use of sealed amphorae for transport"
Do some homework. Produce some evidence. How about an excavated granary with a lot of broken or intact Amphorae which can be shown to have stored grain.
I went to the trouble of finding you sources.
Please have the decency to return the compliment. I am not bothered about what you suspect. I would really like to see some form of evidence.

Otherwise your Persian grain amphorae merely join the super dense Achaemenid camp is yet another construct produced on no evidence which is necessary to allow armies the like of which have never been seen before or since to exist