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

[Jim Webster]

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.

It's perfectly simple. To get the best from every source you have to test it. When we look at Herodotus we have to ask ourselves where he got the numbers and what the Numbers relate to.
Is it the calculated manpower of the Persian army? Was it a document he'd once seen. Was it the size of the army that actually travelled.

So being grown up about it, rather than merely accepting everything a source says, (otherwise we'd be accepting people with one large foot that they use as a parasol to keep the sun off) we try to assess the practicality of it

[Justin Swanton]

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

The camps wouldn't be especially dense and not super-organised in the Roman fashion inasmuch as the Romans made of their camp an entire fort. You really just need enough ground to pitch tents (which would be just big enough to accommodate lying bodies) and include the lifestock and wagons with passageways in between. 8,4 square metres per man including livestock seems manageable. One could also posit larger, looser camps and still remain within the bounds of practicality.

[Jim Webster]

Any examples of real things for comparison?

[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?

Here's something: Caligula's ship-bridge across the Straits of Messena. That's a distance of 3 miles or about 5280 yards. A typical Roman merchant ship was about 16 yards wide. That gives you a ball-park figure of 330 ships. According to Lacius Curtius requisitioning the ships caused a severe famine in Italy, notably Rome, which implies that Caligula had expropriated the Carthage-to-Rome supply fleet, say 300-odd ships, having built the remainder.

If one supposes from this that the entire Roman Mediterranean merchant fleet numbered somewhere between 500 and 1000 ships of all sizes, it would be unreasonable to conclude that the regular Persian merchant fleet numbered more than a couple of hundred vessels. But with 4 years to prepare Xerxes had enough time to construct the extra ships he would need to supply a massive army.

[Justin Swanton]

Any examples of real things for comparison?

This? 400 000 people on 240 hectares for 3 days. 1667 people per hectare = 6 square metres per person. Everyone managed. 

[Jim Webster]

Any examples of real things for comparison?

This? 400 000 people on 240 hectares for 3 days. 1667 people per hectare = 6 square metres per person. Everyone managed. 

nobody is arguing that with post world war 2 technology you can get a lot of people into one place. Woodstock is hardly impressive, If you were to just look at the City of London (or the Square Mile) then the daytime population swells from around 12,000 permanent residents to around 400,000 each day.

But if woodstock is the only historical example you can find for 1.8 million soldiers and 3.6 or thereabouts million camp followers, I think you might as well give up

[Jim Webster]

If one supposes from this that the entire Roman Mediterranean merchant fleet numbered somewhere between 500 and 1000 ships of all sizes, it would be unreasonable to conclude that the regular Persian merchant fleet numbered more than a couple of hundred vessels. But with 4 years to prepare Xerxes had enough time to construct the extra ships he would need to supply a massive army.

and is there any sort of evidence?
Does any of the historians mention building ships? After all they're quite good at talking about the building of warships etc. Building several thousand merchant vessels in a year or so is going to have a big enough impact to get people talking

[Erpingham]

I think we are getting to that point in the argument that usually happens.  A whole host of practical issues are raised as to why 3.5 million people is an impossible number of people to move through this landscape with the level of technology available.  Large numbers of paper calculations are then done to show that, if the army was super-efficient, it could be done.  Super-efficient being at least an order of magnitude higher than any pre-mechanised army and several times more than 20th century armies.

Also, what is the obsession with these bridges?  Can I see any reason to doubt they existed? No.  Does their existence mean 3.5 million men crossed them? No.  Could a much smaller, less efficient, army take seven days to cross? Yes.

I must admit, I think some of the other answers suggest a bit of fantasy is creeping in.  Each day, the army would camp at a site with an irrigation system.  Half the army will cross the river without it fouling the water?  We are Ok with off loading across the beaches the level of supplies because the Romans could feed the population of Rome by sea?  As if they didn't have a huge hard infrastructure to do it?

Are we going to make any further progress or is that going to take too fundamental a collective intellectual shift?

BTW, Loved the Woodstock example Justin.  Instead of super efficient Persians, I've now got in my head a horde of hippies bearing down on Greece

[Flaminpig0]

One thing that isn't clear to me is why the Persians would have felt the need for such an extraordinarily large army.

[Erpingham]

One thing that isn't clear to me is why the Persians would have felt the need for such an extraordinarily large army.

Ah, Ian - this is the bit in QI where the screens flash and the buzzers go off!  The simple answer is "shock and awe".  By delivering a huge army to Greece, the locals will be so overwhelmed by the might of the Great King they will realise that resistance is futile.  They will be even more impressed if it is full of exotic foreigners, showing how wide a territory the Great King already rules. 

However, if one acknowledges the plausibility of this, the literalists pounce and say "told you so", slightly missing the fact that it doesn't require anything more than a very big army by local standards to achieve the effect.  While it does probably move us away from minimalist revisions, and from a "useless mouths" parallel if they are there to pose rather than to fight, it really doesn't resolve the issue.

[Flaminpig0]

One thing that isn't clear to me is why the Persians would have felt the need for such an extraordinarily large army.

Ah, Ian - this is the bit in QI where the screens flash and the buzzers go off!  The simple answer is "shock and awe".  By delivering a huge army to Greece, the locals will be so overwhelmed by the might of the Great King they will realise that resistance is futile.  They will be even more impressed if it is full of exotic foreigners, showing how wide a territory the Great King already rules. 

However, if one acknowledges the plausibility of this, the literalists pounce and say "told you so", slightly missing the fact that it doesn't require anything more than a very big army by local standards to achieve the effect.  While it does probably move us away from minimalist revisions, and from a "useless mouths" parallel if they are there to pose rather than to fight, it really doesn't resolve the issue.

I make a point of only watching TV shows with spaceships, dinosaurs or Kelly Brook in so  aren't aware of QI.

I do wonder about the advisability of taking ancient sources as completely reliable. For example, there is a source covering the Pontic Siege of Rhodes which mentions the goddess Isis getting involved in the fighting  after the Pontics damaged one of her temples.

[Erpingham]

I make a point of only watching TV shows with spaceships, dinosaurs or Kelly Brook in so  aren't aware of QI.

I rarely bother these days - bit samey, despite that greatest of Danes, Sandi Toksvig. 

I do wonder about the advisability of taking ancient sources as completely reliable.

At the risk of launching us off at a tangent, our approach to written sources is fundamental to this and several other long running arguments.  Sources aren't a natural phenomenon but a human artefact.  They have a backstory, which includes who wrote them, where they got their information, who the audience was, what literary conventions were followed and what agenda (overt or covert) the author may have had.  If we don't approach them critically (not necessarily sceptically or cynically), we risk misusing them.  One of the bizarre effects we see from our own "sources first" movement is that their arguments can appear very naive to the more conventionally educated because they deliberately downplay academic critique or even an interdisciplinary approach.  However, they aren't actually naive - they are the result of an independent scholarly approach, which I should respect even if I disagree with it.  That's what keeps me sane in these epic attritional battles anyway

[Patrick Waterson]

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

The Soviet Union before and during collectivisation.  And, to an extent, afterwards.  Communist China during the Great Leap Forward (read Mao's Great Famine by Frank Dikotter if you get the chance).

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.

Even in the event of failure of your principal water supply?  I think you may need to cast your evidential net more widely.

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.

Yes, you did, and thank you.  Unfortunately none of the evidence you produced explains how or why Egypt survived a major (not marginal) famine for seven years or why or how the Achaemenid Empire would find it possible and worthwhile to stock up for years in preparation for a major campaign.  I mentioned amphorae in connection with grain transport.  Whether they were used for storage is conjectural, but it would be interesting to consider what effect this might have on the keeping qualities of their contents.

It's perfectly simple. To get the best from every source you have to test it. When we look at Herodotus we have to ask ourselves where he got the numbers and what the Numbers relate to.
Is it the calculated manpower of the Persian army? Was it a document he'd once seen. Was it the size of the army that actually travelled.

Which is what I am doing.  Objections?

So being grown up about it, rather than merely accepting everything a source says, (otherwise we'd be accepting people with one large foot that they use as a parasol to keep the sun off) we try to assess the practicality of it

Which is what I am doing.  I agree about assessing the practicality; what I do not agree with is beginning with the idee fixe that it is necessarily impossible.  It might be possible or it might not, and we need to understand what the Achaemenid Empire could and, based on its other known and recorded activities, would, do.  This seems to be somewhat different to what people tend, on the basis of a 20th century mentality, to believe.

[Patrick Waterson]

One thing that isn't clear to me is why the Persians would have felt the need for such an extraordinarily large army.

Think like an Achaemenid.  Read Herodotus Book VII (especially 103):

When he heard this, Xerxes smiled and said, "What a strange thing to say, Demaratus, that a thousand men would fight with so great an army! Come now, tell me this: you say that you were king of these men. Are you willing right now to fight with ten men? Yet if your state is entirely as you define it, you as their king should by right encounter twice as many according to your laws. If each of them is a match for ten men of my army, then it is plain to me that you must be a match for twenty; in this way you would prove that what you say is true. But if you Greeks who so exalt yourselves are just like you and the others who come to speak with me, and are also the same size, then beware lest the words you have spoken be only idle boasting. Let us look at it with all reasonableness: how could a thousand, or ten thousand, or even fifty thousand men, if they are all equally free and not under the rule of one man, withstand so great an army as mine? If you Greeks are five thousand, we still would be more than a thousand to one. If they were under the rule of one man according to our custom, they might out of fear of him become better than they naturally are, and under compulsion of the lash they might go against greater numbers of inferior men; but if they are allowed to go free they would do neither. I myself think that even if they were equal in numbers it would be hard for the Greeks to fight just against the Persians. What you are talking about is found among us alone, and even then it is not common but rare; there are some among my Persian spearmen who will gladly fight with three Greeks at once. You have no knowledge of this and are spouting a lot of nonsense."

Observe carefully the mentality, perspective and thinking contained within that assertion.  That pretty much answers the question.

The Achaemenids, broadly speaking, felt that success in battle depended upon two things: bravery and numbers.  Persians had bravery.  Persian armies had numbers.  Put the two together and success was guaranteed.  So they thought.

[Jim Webster]

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

The Soviet Union before and during collectivisation.  And, to an extent, afterwards.  Communist China during the Great Leap Forward (read Mao's Great Famine by Frank Dikotter if you get the chance).

Neither count as living a settled existence, given that they were countries racked by war, and civil war.

After all Khrushchev admitted that the record harvests of the 1960s didn't equal the last prewar harvest of 1913