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

[Justin Swanton]

Not intending to reply in detail to Patrick's long reposte because much has been said since, but I can't let this go by

And what would sir consider to be 'independent evidence'?  Remember we are working from essentially a single source, which means our best bet for getting somewhere is to check it for internal consistency.  Wanting 'independent evidence' is a cop-out.

Independent evidence is from a different source, not copied directly or indirectly from the original.  I do not believe that, if something is internally consistent, it is true.  It is a good sign but not decisive.  To suggest wanting independent evidence is a "cop-out" is a bit alarming.  If we don't test our sources - if we just treat them as infallible - where are we?  And finally, in the context, I was pointing out that just relying on the single source can lead to circular arguments, which this debate is prone to.

This seems to be the core of the problem in this thread. We have only one written source that gives details of the Persian campaign. There's no way of corroborating these details from other sources. So the entire debate revolves around proving or disproving the credibility of that source. Since this involves circumstantial evidence and arguments of probability, none of which are enough to supply scientific proof, we all stay where we are.

Bear in mind that both sides of the argument are making a leap of faith: Patrick and I start with the assumption (belief) that Herodotus is to be relied on unless clear proof can be brought forward that he is wrong (he was wrong in his breakdown of the 1207 Persian warships so, yes, he can be wrong). The other side starts with the assumption that contemporary academics are to be relied on, full stop, and Herodotus is necessarily wrong. None of these academics can bring any scientific proofs to the discussion. They, like Patrick and I, work on circumstantial evidence and arguments (many flawed) of probability.

I can understand both sides' approach and cut the Gordon's knot by considering that Herodotus was clearly trying to write a serious history, and nothing indicates he was part of a propaganda machine a la Goebbels. Hence with something as fundamental as the numbers of the Persian army, he might have been prone to some exaggeration, but not to the degree of making the Persian army ten or twenty times its real size.

[Jim Webster]

What are the major sources of supply of grain in the Persian Empire? Can grain be transported overland from these sources to the Mediterranean coast? Bear in mind that an army doesn't carry more than about a week's grain to feed itself. But a grain caravan can transport a large load of grain much longer distances without having to eat it all.

The basic rule is about ten days and your grain caravan has eaten everything it's carrying
There is a fixed number of drivers needed, they eat.
Working draught animals, along with cavalry horses, need some grain if they're going to work.
This is why the railways opened up America and started the wheat growing on the plains. Because until you had railways there was no way you could have got the wheat out. (The Mississippi river was an exception because obviously it was another form of transport.)

[Justin Swanton]

What are the major sources of supply of grain in the Persian Empire? Can grain be transported overland from these sources to the Mediterranean coast? Bear in mind that an army doesn't carry more than about a week's grain to feed itself. But a grain caravan can transport a large load of grain much longer distances without having to eat it all.

The basic rule is about ten days and your grain caravan has eaten everything it's carrying

Question: if a grain caravan eats all its grain in 10 days, how does an army, with many more men per pack animal, survive for 10 days?

[Erpingham]

Question: if a grain caravan eats all its grain in 10 days, how does an army, with many more men per pack animal, survive for 10 days?

It restocks regularly.  For example, if you restock every five days, it will only eat half its load, leaving half the load weight to provide for accompanying troops. 

[Jim Webster]

It may not be necessary for these areas to grow much more than usual as they supplied customers beyond the Persian Empire. Xerxes could simply have mandated that all surplus grain was not to be exported but stored up for the army. Egyptian grain could have been stored in situ. It would have kept until it was shipped to the major depots around the Aegean in the year before the campaign. Ditto for Syrian/Palestinian grain and grain from drier parts of Asia Minor. Not so sure about grain from the Black Sea. (one consequence of this arrangement is that the folks at home in the Persian hinterland would have had plenty of nosh whilst the army was away  )

nobody produces surplus grain except by accident.
The grain market is a very inelastic thing. If you produce 5% under, you have civil disturbance, riots, and some people will go hungry.
If you produce 5% over, the price collapses because that 5% is frantically chasing any sort of market at all and drives the price down. After all nobody is going to eat an extra meal of barley bread.

So any surplus is accidental and ideally is bought up by the city (as in our Greek example) to keep for the year when there's a drop.

So to guarantee extra grain you've really got to push and pull. You've got to guarantee a market and price, and you've got to encourage people breaking new land.
So you're asking Egypt to feed 6 million people for six months (or thereabouts.)
The population of Egypt in the New Kingdom was four to five million, apparently Josephus gives 7.5 million people for the Ptolemaic period.
So you're asking Egypt to increase it's output by 50% or thereabouts. This means they've got to find 50% more land and 50% more labour

[Jim Webster]

What are the major sources of supply of grain in the Persian Empire? Can grain be transported overland from these sources to the Mediterranean coast? Bear in mind that an army doesn't carry more than about a week's grain to feed itself. But a grain caravan can transport a large load of grain much longer distances without having to eat it all.

The basic rule is about ten days and your grain caravan has eaten everything it's carrying

Question: if a grain caravan eats all its grain in 10 days, how does an army, with many more men per pack animal, survive for 10 days?

seriously, read Engels, he discusses possible routes in great detail.
It is a very serious problem armies faced on long marches. It's one reason why the Roman frontiers tended to follow rivers, because it made supply possible.

[Justin Swanton]

Question: if a grain caravan eats all its grain in 10 days, how does an army, with many more men per pack animal, survive for 10 days?

It restocks regularly.  For example, if you restock every five days, it will only eat half its load, leaving half the load weight to provide for accompanying troops.

Doesn't quite add up. If a mule can carry 100kg of grain (a modest estimate), it can feed 20 men for 5 days. Assume 1 handler to each mule (a generous estimate) and the grain caravan can keep going for 100 days, on the assumption the animals graze off the land.

[Justin Swanton]

What are the major sources of supply of grain in the Persian Empire? Can grain be transported overland from these sources to the Mediterranean coast? Bear in mind that an army doesn't carry more than about a week's grain to feed itself. But a grain caravan can transport a large load of grain much longer distances without having to eat it all.

The basic rule is about ten days and your grain caravan has eaten everything it's carrying

Question: if a grain caravan eats all its grain in 10 days, how does an army, with many more men per pack animal, survive for 10 days?

seriously, read Engels, he discusses possible routes in great detail.
It is a very serious problem armies faced on long marches. It's one reason why the Roman frontiers tended to follow rivers, because it made supply possible.

Yes because armies - many men to each pack animal -  can keep going only for about a week on their supplies before needing replenishment. But a grain caravan is a different story. The main problem would be preserving the grain, which actually wouldn't be a problem in a dry climate with no rainfall during the trip.

[Jim Webster]

Question: if a grain caravan eats all its grain in 10 days, how does an army, with many more men per pack animal, survive for 10 days?

It restocks regularly.  For example, if you restock every five days, it will only eat half its load, leaving half the load weight to provide for accompanying troops.

The problem is that if we take it that the caravan eats its load in ten days, if you transport grain for thirty days, you can restock if you want, but you've still eaten thirty days grain to transport ten days grain for a month.The grain when you hand it over at the end of the month has cost you three times more than it's worth. This is why people didn't do it. It's why caravans tended to trade in high value low weight commodities.

[Erpingham]

Question: if a grain caravan eats all its grain in 10 days, how does an army, with many more men per pack animal, survive for 10 days?

It restocks regularly.  For example, if you restock every five days, it will only eat half its load, leaving half the load weight to provide for accompanying troops.

Doesn't quite add up. If a mule can carry 100kg of grain (a modest estimate), it can feed 20 men for 5 days. Assume 1 handler to each mule (a generous estimate) and the grain caravan can keep going for 100 days, on the assumption the animals graze off the land.

An equine needs roughly 2% of its body weight a day and can carry 20% of its body weight.  So it will eat its load in ten days.  Or to use your example, 100kg represents a 500kg animal (a large mule for the time) eating 10kg per day.  If you are moving between areas where fodder can be independently obtained, you can obviously extend the range.  Caravans on caravan routes may have been able to do this, army baggage trains much less so.

Noting Jim's reply : The caravan thing only works if the load value is greater than the transportation costs.  So, better for the Silk Road perhaps.  But if you can get a premium price (e.g. there's a shortage where you are going and you bought when local surplus has depressed the price) and things are peaceful, so you don't need to pay too many caravan guards, it could be worth it for grain. 

[Justin Swanton]

It may not be necessary for these areas to grow much more than usual as they supplied customers beyond the Persian Empire. Xerxes could simply have mandated that all surplus grain was not to be exported but stored up for the army. Egyptian grain could have been stored in situ. It would have kept until it was shipped to the major depots around the Aegean in the year before the campaign. Ditto for Syrian/Palestinian grain and grain from drier parts of Asia Minor. Not so sure about grain from the Black Sea. (one consequence of this arrangement is that the folks at home in the Persian hinterland would have had plenty of nosh whilst the army was away  )

nobody produces surplus grain except by accident.
The grain market is a very inelastic thing. If you produce 5% under, you have civil disturbance, riots, and some people will go hungry.
If you produce 5% over, the price collapses because that 5% is frantically chasing any sort of market at all and drives the price down. After all nobody is going to eat an extra meal of barley bread.

So any surplus is accidental and ideally is bought up by the city (as in our Greek example) to keep for the year when there's a drop.

So to guarantee extra grain you've really got to push and pull. You've got to guarantee a market and price, and you've got to encourage people breaking new land.
So you're asking Egypt to feed 6 million people for six months (or thereabouts.)
The population of Egypt in the New Kingdom was four to five million, apparently Josephus gives 7.5 million people for the Ptolemaic period.
So you're asking Egypt to increase it's output by 50% or thereabouts. This means they've got to find 50% more land and 50% more labour

To slightly trim the figures, Egypt, Palestine, Syria, Asia Minor and the Black Seas lands are being asked to supply 88% of the requirements of 4 million men for 4 months which is the equivalent of 3,5 million men for 1/3 of a year which is the equivalent of 1,167 million men for a year. The Egyptian population is 7,5 million, so if Egypt alone feeds the army, it is being asked to supply 15,56% of its annual harvest - or just the portion of the annual harvest necessary to feed its own people. Take its surplus into account and the grain supplied by the rest of the Mediterranean coastline and the Black Sea and it doesn't look so unreasonable.

[Justin Swanton]

Question: if a grain caravan eats all its grain in 10 days, how does an army, with many more men per pack animal, survive for 10 days?

It restocks regularly.  For example, if you restock every five days, it will only eat half its load, leaving half the load weight to provide for accompanying troops.

Doesn't quite add up. If a mule can carry 100kg of grain (a modest estimate), it can feed 20 men for 5 days. Assume 1 handler to each mule (a generous estimate) and the grain caravan can keep going for 100 days, on the assumption the animals graze off the land.

An equine needs roughly 2% of its body weight a day and can carry 20% of its body weight.  So it will eat its load in ten days.  Or to use your example, 100kg represents a 500kg animal (a large mule for the time) eating 10kg per day.  If you are moving between areas where fodder can be independently obtained, you can obviously extend the range.  Caravans on caravan routes may have been able to do this, army baggage trains much less so.

Why should the pack animals eat from their grain? If Texan cattle herds of thousands of animals can cover hundreds of miles and remain in good condition solely from living off the land, then a smallish caravan that isn't under the time constraints of an army on the march can surely do the same.

[Jim Webster]

Question: if a grain caravan eats all its grain in 10 days, how does an army, with many more men per pack animal, survive for 10 days?

It restocks regularly.  For example, if you restock every five days, it will only eat half its load, leaving half the load weight to provide for accompanying troops.

Doesn't quite add up. If a mule can carry 100kg of grain (a modest estimate), it can feed 20 men for 5 days. Assume 1 handler to each mule (a generous estimate) and the grain caravan can keep going for 100 days, on the assumption the animals graze off the land.

The rule of thumb is that a mule can carry 20% of its body weight, which is apparently 90kg but that will include the saddle.
One man per mule is merely standard.
So we'll take 80kg as the load (after pack saddle and the handlers bits and bods)
That's 176lbs which at 3lb per man will be about 58 man days,
BUT you've got to feed the mule, because even though animals graze working animals have to be grain fed

For feeding working horses the rule was half a pound of grain per 100lb weight of the horse. Your mule will weigh about 1000lb so if a horse would need 5lb of grain. Because it's a mule it needs less, but because it's working hard because you've got it heavily laden, I'd put it on the same ration as the man. So you'll have about 28 days before you run out. But of course if you're wisely carrying your grain in Amphorae as everybody insisted was necessary to stop it getting damp, the amphora weighs the same as its' load, so you'd end up 14 days from home having eaten everything but with a lot of empty amphorae to admire.

By picking mules you have picked the elite of the pack animal world and modern mules are apparently particularly well bred. The ancient world was more likely to use donkeys or horses which are a lot less efficient, needing to be fed more grain for the load carried.

[Jim Webster]

  so if Egypt alone feeds the army, it is being asked to supply 15,56% of its annual harvest - or just the portion of the annual harvest necessary to feed its own people. Take its surplus into account and the grain supplied by the rest of the Mediterranean coastline and the Black Sea and it doesn't look so unreasonable.

No, it is being asked to increase its production
If you take away 15% of a national harvest and use if for something else people will starve!

[Jim Webster]

Why should the pack animals eat from their grain? If Texan cattle herds of thousands of animals can cover hundreds of miles and remain in good condition solely from living off the land, then a smallish caravan that isn't under the time constraints of an army on the march can surely do the same.

The obvious answer is that the people who used to do this discovered it's necessary

Cattle are ruminants, horses are not. Cattle can put on weight travelling and grazing. (15 miles a day is about the distance they need to travel to not lose weight provided they've got stops for grazing)
They're a different species and do things differently