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

[Jim Webster]

But they are not independent small farmers; they are part of a highly cohesive community, a tribe or a polis.

I am afraid I am going to have to politely disagree with that statement.

Are you entirely sure you wish to disagree with mainstream history?

Well it's never worried you!
And of course the Greek cities and the Thracian tribes weren't a command economy. The idea that Xerxes could merely ordain that an area produced an order of magnitude more food than they usually did and it happened is fantasy

[Patrick Waterson]

So the 6 million that Xerxes dumped on their shores would be a very significant part of the population. I cannot see them feeding a meaningful proportion of that number

Not for any length of time, certainly.  But for a day at a time, to help out the Persians' cross-Aegean supply arrangements, yes.

The Israelites journeyed from Rameses to Sukkoth. There were about six hundred thousand men on foot, besides women and children. 38 Many other people went up with them, and also large droves of livestock, both flocks and herds.

The first census gave 603,550 men over the age of twenty

Pretty damned good for people wandering in the wilderness. Makes old Xerxes look like a complete waste of space

Ramses to Succoth is Egypt, not wilderness (the wilderness came later).  The Hebrews were apparently living off their 'large droves of livestock' as they went, and quite rapidly bringing down the numbers, because by Exodus 16:3 they are already complaining of hunger and need flights of quails and a nightly delivery of manna to sustain them.

Disagree about Greece being dependent upon grain imports:

then you are at odds with most historians. Why do you think the Greeks sent out so many colonists? The main reason historians assure is was because they couldn't feed them at home

The main reason is as Thucydides I.12 tells us:

"Even after the Trojan war Hellas was still engaged in removing and settling, and thus could not attain to the quiet which must precede growth. [2] The late return of the Hellenes from Ilium caused many revolutions, and factions ensued almost everywhere; and it was the citizens thus driven into exile who founded the cities."

He then seems to undermine this somewhat by saying:

"Twenty years later the Dorians and the Heraclids became masters of Peloponnese; so that much had to be done [4] and many years had to elapse before Hellas could attain to a durable tranquillity undisturbed by removals, and could begin to send out colonies, as Athens did to Ionia and most of the islands, and the Peloponnesians to most of Italy and Sicily and some places in the rest of Hellas. All these places were founded subsequently to the war with Troy.

But as the power of Hellas grew, and the acquisition of wealth became more an object, the revenues of the states increasing, tyrannies were by their means established almost everywhere,— the old form of government being hereditary monarchy with definite prerogatives,— and Hellas began to fit out fleets and apply herself more closely to the sea."

What he appears to be saying is that a) the round of civil conflicts following the Trojan War produced colonies in the form of displaced exiles, and b) later on, colonies were sent out deliberately as a means of increasing the home city's influence.

So Thucydides' 'take' is that it was politics which created the colonies; famine and/or grain underproduction had little if anything to do with it (surplus population might, as there was only so much land to work).  In any event, regarding Xerxes, it is Thrace's and Greece's supply potential (and actual) in 480 BC which counts, not in any preceding year.  Nobody was founding colonies in 480 BC (in 465 and again in 437 BC Athens founded one at Amphipolis, but that was for strategic reasons).

And of course the Greek cities and the Thracian tribes weren't a command economy. The idea that Xerxes could merely ordain that an area produced an order of magnitude more food than they usually did and it happened is fantasy

I repeat that they were depleting stocks on an order of magnitude greater than usual, not conjuring extra food of an order of magnitude greater than usual (they did add additional food to make up margins).  One does not need to be a command economy to give up the whole of one's existing stocks (or close to it), just a community in the way of a very large and intimidating army.  Xerxes simply ordained that a certain amount of food be made available; how the locals achieved that was up to them.

[Jim Webster]

So the 6 million that Xerxes dumped on their shores would be a very significant part of the population. I cannot see them feeding a meaningful proportion of that number

Not for any length of time, certainly.  But for a day at a time, to help out the Persians' cross-Aegean supply arrangements, yes.

not even that, 6 million extra mouths is going to swamp them. They might help feed all the canal diggers and road wideners and guards and escorts travelling with them in the first four years.

[Jim Webster]

Ramses to Succoth is Egypt, not wilderness (the wilderness came later).  The Hebrews were apparently living off their 'large droves of livestock' as they went, and quite rapidly bringing down the numbers, because by Exodus 16:3 they are already complaining of hunger and need flights of quails and a nightly delivery of manna to sustain them.

The census figures were taken before and after the wilderness, there was a couple of thousand difference. I merely used them to point out that biblical history tends to produce huge numbers which are unsustainable

It's like Xerxes more than doubling the population of Macedonia

[Jim Webster]

The main reason is as Thucydides I.12 tells us:

"Even after the Trojan war Hellas was still engaged in removing and settling, and thus could not attain to the quiet which must precede growth. [2] The late return of the Hellenes from Ilium caused many revolutions, and factions ensued almost everywhere; and it was the citizens thus driven into exile who founded the cities."

He then seems to undermine this somewhat by saying:

Yes, funnily enough I don't think Thucydides is the last word on the issue. There is a lot of work that has been done since

[Jim Webster]

And of course the Greek cities and the Thracian tribes weren't a command economy. The idea that Xerxes could merely ordain that an area produced an order of magnitude more food than they usually did and it happened is fantasy

I repeat that they were depleting stocks on an order of magnitude greater than usual, not conjuring extra food of an order of magnitude greater than usual (they did add additional food to make up margins).  One does not need to be a command economy to give up the whole of one's existing stocks (or close to it), just a community in the way of a very large and intimidating army.  Xerxes simply ordained that a certain amount of food be made available; how the locals achieved that was up to them.

Patrick please be sensible

A community doesn't just hand over its entire food stocks. They are merely condemning themselves to slow, lingering and unpleasant death.
I think even Herodotus would have mentioned that the entirely population of Northern Greece and Macedonia disappeared through starvation.
similarly a population of perhaps four million does not have the food stocks to feed an army of six million with hangers on. If they have a 10% surplus that will be about it. These are subsistence economies! In some years they'll struggle to feed themselves!
Xerxes can say what he damn well likes but if it's a bad harvest it's a bad harvest and there's not a damned thing anybody can do about it
The whole debate is reaching new levels of fatuous. I realise that in the UK we were the first into the industrial revolution and thus are the European population with least connection to practical agriculture and the land, but some of the arguments I've seen have driven home to me just how disconnected some at least of our population has become

[Erpingham]

Some curious arithmetic here.

1,800 ships for 9,000 tons is 5 tons per ship; on Anthony's figures it should be 25.  The number of ships is thus 1,800/5 = 360.

This is per day.  If you read Justin more carefully, he has ten days worth of ships in the conveyor.  So not so curious after all.

[aligern]

Jim is talking sense here. Pre industrial societies grow their population to the limit of the productive capacity of the good. agricultural land that they control.  If they have plenty of land and a few peaceful generations people are are healthy and able to support more children. The growth will be stopped when marginal land has to be brought into production and that results in a more fragile population, more vulnerable to disease or crop failure.Only a major change in farming methods and transport capability is going to change things. 
There has to be a relationship between the number of people working the land and the amount of food produced.  New land is not sitting around waiting to be put into production, it is in need of clearing, of plowing to break up the soil, likely of fertilising. If an animal or human  dung method of fertilisation is used then there aren't suddenly extra animals around, if they are defecating on new land they are not servicing existing fields. Bringing new land into cultivation requires labour and this labour is not sitting around doing nothing because in a subsistence economy very few people can afford to be waiting around for work to appear.  It is very difficult to massively increase grain production. The only area I can see this being feasible are the rice bowl areas of the Ganges and Yellow river flood plains where you can get two crops per year and even there population will rise to the level of food production available.  Simultaneously  the believers in a 'big army' scenario have the Great king recruiting large numbers of men into the army. and these men have to be fed whilst they are organised and trained and marched to the Hellespont . If the Empire had a population of 50 million then there are roughly 13 million men of military age. Even taking 1.5 million for the army and its logistics component is taking a lot of men out of the food production process at a time when, in theory, more land is to be added and more food produced and an awful lot of these men and their food ( and the animals to be fed,) will be in the wrong places. A man whose food is 300 miles away is still a starving man.
Roy

[Flaminpig0]

But they are not independent small farmers; they are part of a highly cohesive community, a tribe or a polis.

I am afraid I am going to have to politely disagree with that statement.

Are you entirely sure you wish to disagree with mainstream history?

Bit of an Alanis Morrissette situation

[Erpingham]

If we assume that the 400 talents was used to buy subsistence food at equivalent to Athenian prices, grain was 3 drachmae per medimnos.  A Medimnos was 51.84 litres and a litre of grain weighs about 0.8 kg.  There are 6,000 drachmae in an Athenian talent.  I believe therefore a talent would by 82 tonnes.  400 talents would feed 3,280,000 per day.

Another approach is that it is stated by Aristophanes that three people could subsist on half a drachma a day. So 400 talents would feed 4,800,000. 

What we don't know is if the figure of 400 talents is actual and not exaggerated, or what proportion was spent on the lavish hospitality for Xerxes, or even what effect on the market price suddenly needing to find hundreds of tonnes of grain would cause.  But 400 talents is internally consistent.

[Jim Webster]

Some curious arithmetic here.

1,800 ships for 9,000 tons is 5 tons per ship; on Anthony's figures it should be 25.  The number of ships is thus 1,800/5 = 360.

This is per day.  If you read Justin more carefully, he has ten days worth of ships in the conveyor.  So not so curious after all.

you could make a conveyor work but I'd be wary about 'just in time' practices.
After all you could lose days if a sudden storm scatters ships. I think you'd have to work on the principle of 'over -supply' to build up stocks on the beach for the days when you couldn't land stuff.

[Erpingham]

Some curious arithmetic here.

1,800 ships for 9,000 tons is 5 tons per ship; on Anthony's figures it should be 25.  The number of ships is thus 1,800/5 = 360.

This is per day.  If you read Justin more carefully, he has ten days worth of ships in the conveyor.  So not so curious after all.

you could make a conveyor work but I'd be wary about 'just in time' practices.
After all you could lose days if a sudden storm scatters ships. I think you'd have to work on the principle of 'over -supply' to build up stocks on the beach for the days when you couldn't land stuff.

I agree.  The modern concept of "just in time" logistics relies on computers and machine age supply chains. Operating it at the mercy of the weather with no rapid communications seems like tempting fate.  It reflects I think the different approaches being taken by the orthodox and "sources first" proponents.  Instead of checking sources against realities and parallels, "sources first" methodology bends reality round the source.  So, in order to supply the Great Army, Northern Greece must be well populated, highly centralised and producing significant agricultural surpluses.  The fact that the evidence isn't there for this is waved away.  Agricultural production can be boosted 50% overnight and sustained without any major changes that have driven such changes elsewhere in history, like mechanisation. 
To support the conveyor (and credit to Justin he has built in more slack than Patrick allows), we must assume that the weather in the Northern Aegean was very calm with an occassional (rapid onset, rapid passing) storm.  Modern sailing instructions cast doubt on this.  We must also assume over beach supply is easy, when it's actually difficult even with modern landing ships. And so on.
While I think I can see the bones of a much more thorough analysis forming, with a deeper study of things like the demographics and economy of Northern Greece, I don't think anyone has the time and knowledge to do it.  So, we'll just trade random facts until we collapse with exhaustion.

[Justin Swanton]

And of course the Greek cities and the Thracian tribes weren't a command economy. The idea that Xerxes could merely ordain that an area produced an order of magnitude more food than they usually did and it happened is fantasy

I repeat that they were depleting stocks on an order of magnitude greater than usual, not conjuring extra food of an order of magnitude greater than usual (they did add additional food to make up margins).  One does not need to be a command economy to give up the whole of one's existing stocks (or close to it), just a community in the way of a very large and intimidating army.  Xerxes simply ordained that a certain amount of food be made available; how the locals achieved that was up to them.

Patrick please be sensible

A community doesn't just hand over its entire food stocks. They are merely condemning themselves to slow, lingering and unpleasant death.
I think even Herodotus would have mentioned that the entirely population of Northern Greece and Macedonia disappeared through starvation.
similarly a population of perhaps four million does not have the food stocks to feed an army of six million with hangers on. If they have a 10% surplus that will be about it. These are subsistence economies! In some years they'll struggle to feed themselves!
Xerxes can say what he damn well likes but if it's a bad harvest it's a bad harvest and there's not a damned thing anybody can do about it
The whole debate is reaching new levels of fatuous. I realise that in the UK we were the first into the industrial revolution and thus are the European population with least connection to practical agriculture and the land, but some of the arguments I've seen have driven home to me just how disconnected some at least of our population has become

It would help if we take the time frame into account. Xerxes' 3.4 or 5.4 million man army doesn't eat a third or half or more of the available stocks of the population in Thrace and Greece. The army takes about 2 months to travel from the Hellespont to Greece. That's 16,7% of a year, hence 16,7% of the annual food requirement each way - say 8,4% passing through Thrace and 8,4% passing through Macedonia. It also feeds partly off the food dumps and partly off considerable supplies ferried over by the fleet (considerable because when the fleet could no longer function the army was in immediate trouble). I'm guessing Xerxes intended to strip Greece proper to lay up further stocks for the return journey. It is not unreasonable to assume that the allied tribes/nations the Persians passed through were not actually required to supply more than about 10% of their annual harvest, which is something they could manage.

As a possible indicator, the Thasians supplied the Persian army with one meal on behalf of their compatriots on the mainland. Thasian control of the Thracian mainland extended from Stryme in the east to Galepsos in the west, a distance of about 110km in a straight line and probably at least 50% more following the coastline. If the Persians march 20km a day and don't stop for any of the days except the one where they enjoyed their hosts' hospitality, they spent at least 8 days in Thasian territory. So as a ballpark figure, the Persians relied on the locals for 12% of their needs. Doing the sums, that's 12% of 16,7% of their requirements each way = 2% of the annual harvest. Call it 4%. Hardly an intolerable burden on local resources.

[Erpingham]

I'm not sure those figures work.  Lets use a nice round figure army of 4 million and a transit time of 60 days.  We need 240,000,000 person days rations. If this was 10% of the agricultural output of the region on a break even basis, it would produce 2.4 billion rations in a year.  Thats approximately 6.6 million a day.  This is much too high, even by the highest estimates.

If we work it back from (still quite generous) population estimate of 1 million, a break even community produces 365 million rations a year.  An available 10% surplus would therefore be 36.5 million rations, which would feed an army of 608,000 for two months.   Or we can offset it and say our 4 million army would still need to import around 200,000 tonnes of supplies (on a 1kg a day basis).

[Justin Swanton]

I'm not sure those figures work.  Lets use a nice round figure army of 4 million and a transit time of 60 days.  We need 240,000,000 person days rations. If this was 10% of the agricultural output of the region on a break even basis, it would produce 2.4 billion rations in a year.  Thats approximately 6.6 million a day.  This is much too high, even by the highest estimates.

If we work it back from (still quite generous) population estimate of 1 million, a break even community produces 365 million rations a year.  An available 10% surplus would therefore be 36.5 million rations, which would feed an army of 608,000 for two months.   Or we can offset it and say our 4 million army would still need to import around 200,000 tonnes of supplies (on a 1kg a day basis).

One other consideration - see my modified post.