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

[Justin Swanton]

We have five depots mentioned so each is going to hold 240,840 tons of wheat which means each granary has 564 bins each about 60 x 40 x 9 feet 
Obviously different bin sizes can be chosen but for smaller ones you need more, and for storing grain in amphorae or sacks you need more again

About 390 yards square for a depot. Not inconceivable. The Long Walls of Athens, built of stone and each about 6km long, took 4 years to build.

Oh they could have been built, but we'd struggle not to find them. Because there'd be a lot of internal walls (and good thick internal walls because grain 'pushes')
Granaries survive well in the archaeological record because they have to be so well built. 

Presuming they were temporary wooden structures built in a depot port, and later removed and built over because there was no further need of them, would we find any trace of them now?

[Flaminpig0]

Have you considered the makeup of the Persian host.  Large amounts of subject peoples, un willing and unlikely to be disciplined.

I submit no king would allow them to pick their own route or remain far out of sight of reliable troops to keep them under control.

I doubt they were that undisciplined; the one case of 'insubordination' (at Plataea) involved an officer, not soldiery, disobeying orders and leaving early with his contingent.  Artabazus had taken the oracles to heart and decided he wanted no part in any upcoming defeat, so hied off back to Asia with his entire corps.  They seem to have obeyed him without question.

The Achaemenids anyway seem to have had had their own system which substituted threat of the whip for actual discipline except among Persians, Medes and similar high-status troops.

Leaving side the idea of just how regular the 1,700,000 or so Persian Infantry were apart from Herodotus is there any other evidence for these whip men? whipping a large number of armed men seems to be an invite for disaster.

[Erpingham]

doesn't Herodotus mention 5 depots?

I believe so.    Excuse my ignorance but do we know where they were?  These presumably are where the fleet is moving stuff from, as they won't supply an army with a seven day supply establishment.  Justin clearly envisages wooden depot structures to service the army on the march, with very short operational lives, which is consistent.  We should be able to find some trace of these - we have various Roman temporary camps from across the empire which have been located.

If we are saying that the Athenian Long Walls are the sort of evidence we are looking for for the big depots, although Piraeus is very built up, we can still detect these.  So they should still be archaeologically detectable even if below modern cities.  It maybe that we have of course detected bits of them but haven't joined the dots to reconstruct them as mega-depots.

[Flaminpig0]

  Besides, it soldiered in the Biblical, not the Napoleonic, tradition.

What do you mean by 'soldering in the Biblical tradition'?  it could be read as either something pertaining to the bible or something very large indeed- neither of which really seem to be what you are saying.

I refer to the period c.3,200-500 BC and the Egyptian, Assyrian, Babylonian, Hebrew, Chaldean, Median etc. cultures, with the Sumerians getting a look in.  'Biblical' is an easy temporal designation for this period, cf. 'Islamic' for the period of Muslim expansion and subsequent caliphates.  The art of warfare developed considerably during this period, but certain elements seem to have remained constant more or less throughout.

The period is marked by large (some very large) armies, cross-country travel by those armies, big battles (mostly) and store-cities along the route of march providing supply for those armies.

I thought that might be what you meant, but is there really evidence of large- to pick an example- Hebrew armies?  Also these large armies are considerably smaller than Xerxes which I think we are all agreed was an extraordinary event. What make you think that 'biblical' methods of logistics would be scale up to the efficiency needed to support Xerxes army of 2 or so million?

[Jim Webster]

We have five depots mentioned so each is going to hold 240,840 tons of wheat which means each granary has 564 bins each about 60 x 40 x 9 feet 
Obviously different bin sizes can be chosen but for smaller ones you need more, and for storing grain in amphorae or sacks you need more again

About 390 yards square for a depot. Not inconceivable. The Long Walls of Athens, built of stone and each about 6km long, took 4 years to build.

Oh they could have been built, but we'd struggle not to find them. Because there'd be a lot of internal walls (and good thick internal walls because grain 'pushes')
Granaries survive well in the archaeological record because they have to be so well built. 

Presuming they were temporary wooden structures built in a depot port, and later removed and built over because there was no further need of them, would we find any trace of them now?

Given that they had to be handy for somewhere where it was easy to unload boats, and had to have a decent water supply (for the staff working there as well as passing 'customers' I'd suggest that if they were the size they would have to be for that sheer number of men, they'd have become towns. The sheer amount of 'recyclable' timber already cut and dressed would have people sailing from Asia minor and Greece just to load boats with it!
Personally given locally available building materials, I think it would be faster and easier to put up low buildings with local stone which would be far easier to keep the contents dry
The roofs would present an interesting issue. You couldn't use thatch, you'd almost certainly have to use clay tile, even if you had timber walls. So the sites would probably be easy to find now because of broken roofing tiles, plus broken amphorae from wine and oil transport.

Also thinking about it, you'd need a lot of clear, 'concreted' area where you could empty a bin, re-dry the grain that's got a bit fusty, and then load the grain back into the fumigated bin

[Jim Webster]

Rome had three hundred horrea or granaries (but they probably stored more than just grain, oil was stored in them as well. ...
As for how much grain per man, 1 choinix per day (1.5lb) isn't enough to keep a man alive and active (Romans and ACW had 3lb a day). So if 1 choinix is right it had to be supplemented by something, but that too would have to be carried in and stored. So I'll assume 3lb per day. ...
So a million men will need 1338 tons a day (or half that and 3400 cattle slaughtered a day)
So for six million men (because there's the fleet and all those engineers working etc) we need 8028 tons a day.

Earlier, Jim, you were talking about the difficulties of storing grain for several years. So given that Xerxes was allegedly preparing this expedition for four years, I wonder how much spoilage we should allow for.

I'm assuming that they practiced good rotation of stocks, used sacks for haulage and storage, and that most of the grain in store was from the previous year's harvest and not before.
So given the lack of facilities for consumer complaints (    ) I think they'd be able to keep on top of things. Anything a bit iffy might be fed to draught animals.
If they were really on top of the ball I'd suggest you might get away with 10% waste (and some of that would be straight pilfering)

If they really were storing grain for multiple years, unless each year they emptied each bin, re-dried it in the sun and fumigated the bin whilst it was empty, then you could start getting major losses. You might find that this building was fine and the one next to it was a salvage operation and you might save 20%.

The manpower in these depots, if they're having to re-dry grain and re-store it is going be be large.
Imagine you have to deal with five hundred bins, each of which has four hundred tons of grain in it. And you've got to manually empty the bin, dry the grain and then manually refill the bin. Of course a small team could fumigate the bin whilst the main labour force is drying it and carrying it back into an already fumigated bin.

[Dangun]

I did not read all of the very erudite replies to this and I am away from my library at the moment but as I recall didn't Engels cover this a bit in his most excellent "Alexander the Great and the Logistics of the Macedonian Army"?

Yes. Engels has been mentioned a couple of times. But the literalists are unimpressed.

[Justin Swanton]

Here's an experiment in underground grain storage. The bottom line seems to be that properly-dried grain with a moisture content of 15% or less can last several years. Drying out grain to this extent is a fairly straightforward process in a climate like Egypt's. If stored in sealed amphorae for the voyage to the depots in Greece the moisture content shouldn't rise significantly as amphorae are impermeable to water.

And no, it doesn't have to be underground silos.

[Jim Webster]

Here's an experiment in underground grain storage. The bottom line seems to be that properly-dried grain with a moisture content of 15% or less can last several years. Drying out grain to this extent is a fairly straightforward process in a climate like Egypt's. If stored in sealed amphorae for the voyage to the depots in Greece the moisture content shouldn't rise significantly as amphorae are impermeable to water.

And no, it doesn't have to be underground silos.

I'm not sure how transferable the results would be to Greece. "Yuanbaoshan lies in 118°93'£, 42°6TN, where belongs to cold zone and sub-dry continent climate with 23. 7°e of maximum averaged monthly temperature, minimum monthly temperature IS - 30.1 °e, lowest dally temperature is - 31.2°e , and top dally temperature IS 42"C. The averaged annual temperature IS 6. 7°e There are 130 days with mean temperature 0 degrees C. The annual mean rainfall reaches 394.7mm while the evaporation reaches 1880mm. The
deepest frozen soil layer IS 1.3 meter thick. The constant temperature of the layer 15 meters beneath the earth is 8.0 - 9 .ooe, resulting in stable low temperature in this granary.

but if the Persians used this technique it is going to be so easy to find these places for archaeologist. Each of these 5 stock piles has 500 underground bins, each 60x40 feet and about six meters deep (because you have to go 4 meters down for the temperature control)
The sheer quantity of grain to be stored means that you need a vast storage area. And the amount of excavation they'd have to do would mean we'd probably be able to pick out these places on google earth!

[Justin Swanton]

Here's an experiment in underground grain storage. The bottom line seems to be that properly-dried grain with a moisture content of 15% or less can last several years. Drying out grain to this extent is a fairly straightforward process in a climate like Egypt's. If stored in sealed amphorae for the voyage to the depots in Greece the moisture content shouldn't rise significantly as amphorae are impermeable to water.

And no, it doesn't have to be underground silos.

I'm not sure how transferable the results would be to Greece. "Yuanbaoshan lies in 118°93'£, 42°6TN, where belongs to cold zone and sub-dry continent climate with 23. 7°e of maximum averaged monthly temperature, minimum monthly temperature IS - 30.1 °e, lowest dally temperature is - 31.2°e , and top dally temperature IS 42"C. The averaged annual temperature IS 6. 7°e There are 130 days with mean temperature 0 degrees C. The annual mean rainfall reaches 394.7mm while the evaporation reaches 1880mm. The
deepest frozen soil layer IS 1.3 meter thick. The constant temperature of the layer 15 meters beneath the earth is 8.0 - 9 .ooe, resulting in stable low temperature in this granary.

but if the Persians used this technique it is going to be so easy to find these places for archaeologist. Each of these 5 stock piles has 500 underground bins, each 60x40 feet and about six meters deep (because you have to go 4 meters down for the temperature control)
The sheer quantity of grain to be stored means that you need a vast storage area. And the amount of excavation they'd have to do would mean we'd probably be able to pick out these places on google earth!

Doesn't have to be underground silos. Just dry grain kept dry. Wheat with a moisture content of 11.8% can last 15 years with no appreciable change when stored at a fairly constant temperature of around 10 degrees celsius. The report emphasises that the lack of oxygen also contributes to the preservation process. I submit that dry grain in a sealed amphora where moisture and oxygen remain low will last 4 years without too much trouble even if the ambient temperature is much higher.

As a final point the grain doesn't have to be moved to Thrace and Macedonia right from year one. It can be stored in Egypt where the climate facilitates preservation and transported by ship to the depots only in the year preceding the invasion.

[Erpingham]

On amphorae, are we able to check what the usual operation of the day was?  Would the grain have been stored in the depot in amphorae or in bins?  Would amphorae have been filled just before transport?  On permeability, incidentally, the amphorae were naturally permeable but sealed internally for carrying liquids.

If we assume that amphorae were in use to carry grain because of the issues of protecting them during beach unloading (I don't think we have evidence of amphorae as the usual grain carrying method, though we know they could be used for that), are they stored in the landing depots in the amphorae and are they issued to the army as is?  We haven't really considered the effect of issuing the grain in amphorae on the supply train - an amphora roughly weighs the same as its contents, so will double the number of animals required.  It maybe though it was transfered into something lighter (baskets? sacks?), which would leave us with a lot of amphorae at the depot.  They could potentially be reloaded returning transports or maybe discarded.  In any case, there are going to be scattered amphorae fragments around the depot, which should help identify it to archaeologists.

[Duncan Head]

I'm assuming that they practiced good rotation of stocks, used sacks for haulage and storage, and that most of the grain in store was from the previous year's harvest and not before.

Not sure we can assume that, because in Year 2 there isn't a huge army there to eat most of Year 1's grain and replace it with Year 2's. This isn't like a permanent settlement - you're stockpiling grain that there isn't a requirement for until Year 4 (or is it 5?).

[Erpingham]

While exploring amphorae I chanced upon this.  Interesting because its all about amphorae as shipping containers, rather than about types and sequences. 

[Jim Webster]

Here's an experiment in underground grain storage. The bottom line seems to be that properly-dried grain with a moisture content of 15% or less can last several years. Drying out grain to this extent is a fairly straightforward process in a climate like Egypt's. If stored in sealed amphorae for the voyage to the depots in Greece the moisture content shouldn't rise significantly as amphorae are impermeable to water.

And no, it doesn't have to be underground silos.

I'm not sure how transferable the results would be to Greece. "Yuanbaoshan lies in 118°93'£, 42°6TN, where belongs to cold zone and sub-dry continent climate with 23. 7°e of maximum averaged monthly temperature, minimum monthly temperature IS - 30.1 °e, lowest dally temperature is - 31.2°e , and top dally temperature IS 42"C. The averaged annual temperature IS 6. 7°e There are 130 days with mean temperature 0 degrees C. The annual mean rainfall reaches 394.7mm while the evaporation reaches 1880mm. The
deepest frozen soil layer IS 1.3 meter thick. The constant temperature of the layer 15 meters beneath the earth is 8.0 - 9 .ooe, resulting in stable low temperature in this granary.

but if the Persians used this technique it is going to be so easy to find these places for archaeologist. Each of these 5 stock piles has 500 underground bins, each 60x40 feet and about six meters deep (because you have to go 4 meters down for the temperature control)
The sheer quantity of grain to be stored means that you need a vast storage area. And the amount of excavation they'd have to do would mean we'd probably be able to pick out these places on google earth!

Doesn't have to be underground silos. Just dry grain kept dry. Wheat with a moisture content of 11.8% can last 15 years with no appreciable change when stored at a fairly constant temperature of around 10 degrees celsius. The report emphasises that the lack of oxygen also contributes to the preservation process. I submit that dry grain in a sealed amphora where moisture and oxygen remain low will last 4 years without too much trouble even if the ambient temperature is much higher.

As a final point the grain doesn't have to be moved to Thrace and Macedonia right from year one. It can be stored in Egypt where the climate facilitates preservation and transported by ship to the depots only in the year preceding the invasion.

If it's in amphorae, that means at 30lb per amphora and 89,913,600 of them to transport 1,204,200 tons of grain.
If they used amphorae there should be shoals of broken amphorae in places.

The reason the grain was buried was to get the temperature stable and low. Keeping it low is no going to be easy in Egypt.
Don't be too enthusiastic about just keeping oxygen out. You can then get an anaerobic fermentation. (Silage is just grass preserved by anaerobic fermentation.) All it means with this is that your wheat ends up getting pickled in lactic acid, which isn't going to be particularly good

[Jim Webster]

I'm assuming that they practiced good rotation of stocks, used sacks for haulage and storage, and that most of the grain in store was from the previous year's harvest and not before.

Not sure we can assume that, because in Year 2 there isn't a huge army there to eat most of Year 1's grain and replace it with Year 2's. This isn't like a permanent settlement - you're stockpiling grain that there isn't a requirement for until Year 4 (or is it 5?).

I'd assume that you'd have the initial stocks to feed your people in place. Your canal diggers and road clearers and suchlike.
The actual stockpiles would have to be in the grain producing area where you could rotate them.
You'd only shift the bulk of the stuff north in the year before the army was going to travel.