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

[Flaminpig0]

Yes I'm beginning to think that the Persians did have something like 3 or 4 'logistics/supply chain' people to every fighting man for this campaign.
Think of the engineering staff they sent ahead build roads and level ground. Almost by definition this couldn't have been local corvee labour because they'd already asked the locals to increase agricultural output and stockpile food.
When you take into account men unloading boats and managing and guarding the stores, they're all going to have to be fed, and if they're just fed from local surplus, it merely means that less local surplus is available to supply troops and the baggage travelling with them.

Another issue is did the Persian troops have personal servants much as a Greek Hoplite might have,of course that adds to the numbers of the invasion force -  so depending on what your starting point is it could reach towards 6 million or possibly more. Or twenty one million if each Persian the equivalent to the Spartan 7 helots per Hoplite.

[Erpingham]

I believe Herodotus gives as about as many camp followers as combatants.  But this does not mean elite units didn't have multiple servants and line units shared one between several. Also, its not clear to me whether the labour corps is numbered in the army or the camp follower totals - Justin may be able to help there.

[Flaminpig0]

I believe Herodotus gives as about as many camp followers as combatants.  But this does not mean elite units didn't have multiple servants and line units shared one between several. Also, its not clear to me whether the labour corps is numbered in the army or the camp follower totals - Justin may be able to help there.

So using Herodotusian numbers we are looking at an invasion force of roughly 5 million which for comparison is about half the size of the Greek population at the time.

[Erpingham]

When these numbers are added to the numbers from Asia, the sum total of fighting men is two million, six hundred and forty-one thousand, six hundred and ten.   This then is the number of soldiers. As for the service-train which followed them and the crews of the light corn-bearing vessels and all the other vessels besides which came by sea with the force, these I believe to have been not fewer but more than the fighting men. Suppose, however, that they were equal in number, neither more nor fewer. If they were equal to the fighting contingent, they made up as many tens of thousands as the others. Book 7 185-186

Note that Herodotus includes naval units in the count of fighting forces.  There are about half a million people with the fleet (though an inconsistency in the fleet makeup means his estimate (he admits its an estimate) may be too high).  So the land forces, inclusive of tail, must be over the four million mark.

[Flaminpig0]

When these numbers are added to the numbers from Asia, the sum total of fighting men is two million, six hundred and forty-one thousand, six hundred and ten.   This then is the number of soldiers. As for the service-train which followed them and the crews of the light corn-bearing vessels and all the other vessels besides which came by sea with the force, these I believe to have been not fewer but more than the fighting men. Suppose, however, that they were equal in number, neither more nor fewer. If they were equal to the fighting contingent, they made up as many tens of thousands as the others. Book 7 185-186

Note that Herodotus includes naval units in the count of fighting forces.  There are about half a million people with the fleet (though an inconsistency in the fleet makeup means his estimate (he admits its an estimate) may be too high).  So the land forces, inclusive of tail, must be over the four million mark.

It might worth considering that these numbers are based upon Xerxes review of the troops at Doriskos- obviously they don't include those who deserted or otherwise dropped out so the original starting army would be even larger. Possibly considerably so bearing in mind the irregular nature of the host.

As an aside  I cant help but note that if this force for the most part never returned to Persia etc  the invasion would become one of the greatest disasters in human history.

[Patrick Waterson]

Sadly I have none of an army advancing on so narrow a frontage, but I have two of Persian armies advancing on a considerably greater frontage.  The question is: once I cite them, is Jim going to accept that Persian armies did happily and habitually advance on a wide front rather than in a long column of route?

Looks like a major change of tack there Patrick.  The narrow column has been one thing that everyone so far has accepted - we are working with Justin's 300 metre road.  Are you now proposing that the army advanced on a wide front?  If so, how did they do this, if their advance has been predicated by Justin on massive advanced engineering works and single mega camps?  How does it fit with the supply by sea and the depot strategy?  It certainly gives a new perspective on choke points, with the army expanding and contracting more regularly than would be required by Justin.

I would not say a 'major change of tack', rather a possible development of the same principle.  Justin has been trying to wean people away from the idea that the Achaemenids moved solely along roads (which did not then exist apart from the mesenger highways in side the Rersian Empire) but instead travelled in bulk across the country.  The above instances would seem to support that idea, because although the army of Artaxerxes could be assumed to be advancing in order of battle the army of Shapur could not.  The fact is we have very few descriptions of an Achaemenid army on the march, and the other one (Herodotus VII.40-41) has already been hinted at by Aaron:

First went the baggage train and the beasts of burden, and after them a mixed army of all sorts of nations, not according to their divisions but all mingled together [ou diakekrimenoi = not separated]; when more than half had passed there was a space left, and these did not come near the king.

[Description of Xerxes and escorting troops omitted]

After these there was a space of two stadia, and then the rest of the multitude followed all mixed together [anamix = promiscuously, pell-mell rather than 'mixed'].

Distances other than those separating the two contingents of ordinary troops from the King's are not given, but one gets a similar impression of a vast mass rather than a narrow column.  Whether this would have been 300 yards wide or 3,000 or whatever I have no idea.

With regard to 'choke points', the mass would tend to flow around these, with just the wheeled transport and perhaps the royal entourage having to pass through the 'choke'.  The army would not, as I understand it, contract to go through a pass but rather scramble over such passable terrain as they could find, leaving the pass proper for those who had no option but to use it and those who did not wish to get their royal robes dirty.

Encamping and resupply by sea would be much as previously considered, in that the army would camp along rivers and along beaches, the different contingents being marshalled into places allocated to them.

[Patrick Waterson]

"The Persian fleet put to sea and reached the beach of the Magnesian land, between the city of Casthanaea and the headland of Sepia. The first ships to arrive moored close to land, with the others after them at anchor; since the beach was not large, they lay at anchor in rows eight ships deep out into the sea."

If I read this correctly, one eighth of the ships 'moored close to land' without actually beaching.  The rest dropped the hook (or stone) in open water.

They can't do this for long, because they need to rewater and resupply.  Galleys normally beach to do this.  Riding at anchor would be highly risky - galleys were very vulnerable to the weather.  In fact, why build a canal to avoid storms if you are going to lie offshore everyday?

Because the fleet is so big.  In point of fact they were hit by a storm the very next day, with considerable losses.  The spring of 480 BC had more than its fair share of stormy weather; the Athos canal probably saved the Persians the equivalent of one storm, but there were - apparently unexpectedly - two more in the offing.

The fleet did not lie offshore every day unless they had to.  Remember when they were all pulled up onto the beach at Doriscus and dried out there while Xerxes was numbering his army?  One wonders whether someone had belatedly realised this would be the last chance many of them would get for some time.

[Jim Webster]

With regard to 'choke points', the mass would tend to flow around these, with just the wheeled transport and perhaps the royal entourage having to pass through the 'choke'.  The army would not, as I understand it, contract to go through a pass but rather scramble over such passable terrain as they could find, leaving the pass proper for those who had no option but to use it and those who did not wish to get their royal robes dirty.

How on earth do the mass tend to flow around a choke point? If you can flow round it, it isn't a choke point.

[Patrick Waterson]

Note that Herodotus includes naval units in the count of fighting forces.  There are about half a million people with the fleet (though an inconsistency in the fleet makeup means his estimate (he admits its an estimate) may be too high).  So the land forces, inclusive of tail, must be over the four million mark.

1.7 million Achaemenid infantry, 20,000 Achaemenid mounted and 300,000 Thracians gets us to 2 million plus; adding camp followers and support personnel at Herodotus' estimated 1:1 ratio would give around 4 million.  Note that Herodotus does not differentiate between support personnel on land and support personnel crewing the corn ships etc. (although one gets the impression he is counting the latter twice at Thermopylae) so the actual terrestrial as opposed to aquatic component might be lower than 4 million.

As an aside  I cant help but note that if this force for the most part never returned to Persia etc  the invasion would become one of the greatest disasters in human history.

I have been trying to track down a half-remembered reference which says almost exactly that.  Apparently, if I remember correctly, it m aintains that the loss of manpower crippled the Achaemenid Empire for about a generation and caused shortages in agruculture and just about everything else.

[Patrick Waterson]

How on earth do the mass tend to flow around a choke point? If you can flow round it, it isn't a choke point.

Because we think of it as a 'choke point' whereas they thought of it as a narrow flat bit that has to be left for the use of Their Excellencies and the chaps with wheels while the rest of us go up another [expletive deleted] hillside again.

[Jim Webster]

How on earth do the mass tend to flow around a choke point? If you can flow round it, it isn't a choke point.

Because we think of it as a 'choke point' whereas they thought of it as a narrow flat bit that has to be left for the use of Their Excellencies and the chaps with wheels while the rest of us go up another [expletive deleted] hillside again.

remember some of these choke points are choke points because armies couldn't just go up the hillside

[Justin Swanton]

How on earth do the mass tend to flow around a choke point? If you can flow round it, it isn't a choke point.

Because we think of it as a 'choke point' whereas they thought of it as a narrow flat bit that has to be left for the use of Their Excellencies and the chaps with wheels while the rest of us go up another [expletive deleted] hillside again.

remember some of these choke points are choke points because armies couldn't just go up the hillside

From what I've been able to see from Google maps, there was actually no chokepoint between Asia Minor and Thermopylae that was not either at least 600m wide or could not be bypassed over the hilly ground on either side. The Greeks initially took up position at Tempe until they learned that that chokepoint could be bypassed over the ground to the north, and then stood at Thermopylae precisely because it could not be bypassed until the Persians learned of the goat path. Looking at the terrain just west of Mount Kallidrome the ground is not that steep and not especially broken. It's covered with trees which possibly is what made Xerxes discount it as a route around Leonidas until someone told him there was a path through them.

For interest, here is Thermopylae. Mount Kallidrome with Leonidas' memorial below:



My proposed route around the mountain that takes the least sloping terrain. The contours are at 40m intervals:



A few close ups of the ground west of the mountain (just off left of the pictures). Not terribly formidable if you have a path through the trees:

[Jim Webster]

Lucky for the Greeks Patrick wasn't in charge. He's have just sent the entire PBI straight up the hillside with orders to reform when they hit level ground again

Wonder why the Persians never thought of that

[Patrick Waterson]

At least we seem to be rid of the 'choke points' - up to Thermopylae, at any rate.

[Erpingham]

At least we seem to be rid of the 'choke points' - up to Thermopylae, at any rate.

Just a reminder that the "choke points" issue came up again when the idea was floated of the army advancing on a broad front.  Justin's work on choke points is still predicated on a 300m road.  Patrick's speculated 3000m wide advance would generate more "choke points" if we define them as when the army has to narrow frontage.