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

[Justin Swanton]

For a Persian army of 480 000 men, or just 200 000 men, to march to Greece, it would either have to do it in a string of separate corps a la Napoleon all following each other on the same road, or take separate routes along pathways broad enough for a column at least 4 men wide. Any evidence for either option?

I thought we had no roads at all (according to Patrick)?  The answers have to be somewhere in the geography - could the army advance along several parallel routes?  So far, we've assumed no.  Also, there has been an emphasis on the whole army moving between camps a day apart every day.  The idea that the same routes and camps were used over multiple days was rejected.  If the army is spread over several days in a long column it brings new march rate issues (will the disturbed and manured ground slow the march of the rear elements) logistical issues (fodder will be depleted at the camp site, stockpiles may no longer be adequate for the rear units) and certainly some hygiene issues of reuse of fouled ground.

This occurred to me as well. Right now I've put aside the 3,4 million man army and am looking at the problem of moving 480 000 or just 200 000 men in undeveloped Thrace and Macedonia with the presumption there is no clearing of broad avenues, the Persians are not cross-country types anyway, and the army moves exclusively along the track(s) it finds there. Just how feasible is that?

Incidentally, I find it an interesting coincidence that the size of a Roman field army throughout the history of the Republic and Empire seems to hover around the 20 000 to 30 000 mark, regardless of the size of its component legions, and that this matches the size a French corps - all these units expected to march from camp to camp along a single road/track. Hannibal seems to have pushed the limits on his Italian campaign with 38 000 infantry and 8000 cavalry (which all marched along a single mountain track through the Alps).

[Justin Swanton]

So if the Persians can clear 150 metres of pathway, what's stopping them clearing 600 metres? They had 4 years to do it.

The basic maths is that it would take four times as long. But actually it would take far longer because the area nearer the central line of the road/track would be easier to work on.
As an interesting side issue, because nobody was actually using this notional 600 meter frontage in the three years or four years before the army came through, unless you went to the trouble of physically uprooting stuff and burning it, you'd probably find that you'd have scrub and brush growing again so it would still need redoing.

That occurred to me. Spend 3 years clearing away the big stuff like trees then the last year removing the smaller stuff that grows in a few months like shrubbery.

[Jim Webster]

This occurred to me as well. Right now I've put aside the 3,4 million man army and am looking at the problem of moving 480 000 or just 200 000 men in undeveloped Thrace and Macedonia with the presumption there is no clearing of broad avenues, the Persians are not cross-country types anyway, and the army moves exclusively along the track(s) it finds there. Just how feasible is that?

Incidentally, I find it an interesting coincidence that the size of a Roman field army throughout the history of the Republic and Empire seems to hover around the 20 000 to 30 000 mark, regardless of the size of its component legions, and that this matches the size a French corps - all these units expected to march from camp to camp along a single road/track.

A lot will depend on camp discipline. The better is is, the less problem you have with units marching from camp to camp. If you had a number of camps, and perhaps even a thousand men per camp, permanently stationed as military police, they could probably ensure the camps weren't too bad, troops used latrines etc.
But there again, if Persian marching camps were as informal as Greek marching camps, it might be that you had everybody marching the same distance, but camping two miles apart.(so on the first day the first corps marched 16 miles, the second 14 miles, the third 12 miles etc On the second day everybody marched 16 miles.) This way with your corps of 20,000, yes you'll march through old camp sites, (although they could be kept off the road) but each corps will have a fresh site, with untouched fodder for the servants to collect.
You could probably have seven corps and run this system, and nobody has to march too far.
If you've done some road tidying, perhaps cleared 'trails' inland (no point in clearing a full 3000 yards, just clear 150 yards, twice, you could perhaps double the number of corps. But then for collecting fodder the southern road would have to collect 'south' and the northern road 'north'
That would give you 14 corps of 20,000 men or pretty close to 300,000.

The advantage of this number following two parallel trails is that you're marching on a relatively narrow front (when dealing with choke points. You're foraging more widely but servants can forage on slopes when the army is camped and don't slow the army down

[Jim Webster]

That occurred to me. Spend 3 years clearing away the big stuff like trees then the last year removing the smaller stuff that grows in a few months like shrubbery.

I don't think you'd need to do it. Just clear 40 yards. Then 100 yards north clear another 40 yards. Then you've got two 'roads' and you can put your troops down like i mentioned above

[Patrick Waterson]

Observe that while the Spartans were moving through the hills, the Athenians 'had taken the way of the plain'.  These contingents were travelling in parallel, i.e. on a broad front, not in series (as would be the case with a march column).  This is confirmed by what happened next.

Nowhere does this even hint that this was done by troops shambling like locusts on a broad front. It could have been done by contingents forming up into columns two or three wide (or given the size of some of the contingents, one man and his servant wide, and pulling back)

Actually it does.  If the Athenians had been in a long narrow column, they would either have been chewed up piecemeal by the Medising Greeks (who, like their Persian friends, were not fussy about advancing in a disorderly swarm) or they could have attempted to assemble a rearguard while the bulk of the column departed to aid the Spartans.  Neither of these things happened.  The Athenians were able to form up quickly enough to fend off their attackers, which precludes their having been in a long, thin column of march, and were unable to send the Spartans any assistance, which means their foes were able to assemble quite quickly, too.

[Patrick Waterson]

Any army marching and being harassed by cavalry stays in a tight column, probably on a frontage of ten to eight wide, because then you're in line of battle if you turn 90 degrees.

The problem with this comment is that when the Greeks moved out they were not being harassed by cavalry, nor did they expect to be (if they had expected it, Pausanias would have called over the Athenians a lot sooner).

Napoleons columns always took a road.
Always.

Infantry to the ditch alongside, guns and horses on the road itself, with half width so that messengers could return along it, and a crash was not going to block the entire army.

Erm ... Mark, helpful though that is for those of us interested in the Napoleonic period, the Achaemenid army had a) no guns and b) no roads (or ditches) to follow.  Besides, it soldiered in the Biblical, not the Napoleonic, tradition.

So far in this thread we have seemingly grudgingly accepted that naval supply is possible, that storing up the necessary grain is possible, that Xerxes' army occupied a very large camp and that not all armies everywhere march exclusively two to four wide along roads.  We have not studied the demographics of the Persian Empire in any detail (one reason being that there is not a lot of detail to study), but population estimates run from 17 million to 55 million for this period, so a fighting manpower of a couple of million backed by a similar number of noncombatants is by no means out of the question.

The big hang-up seems to be moving the army.  Because we cannot think of methods which satisfy everyone we seem to be adopting a dog-in-the-manger attitude and assuming it could not be done.  We seem incapable of allowing for the possibility that people with a lot more experience of moving large Achaemeneid armies than ourselves might have thought of and implemented methods beyond our ken.

[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.

[Jim Webster]

Observe that while the Spartans were moving through the hills, the Athenians 'had taken the way of the plain'.  These contingents were travelling in parallel, i.e. on a broad front, not in series (as would be the case with a march column).  This is confirmed by what happened next.

Nowhere does this even hint that this was done by troops shambling like locusts on a broad front. It could have been done by contingents forming up into columns two or three wide (or given the size of some of the contingents, one man and his servant wide, and pulling back)

Actually it does.  If the Athenians had been in a long narrow column, they would either have been chewed up piecemeal by the Medising Greeks (who, like their Persian friends, were not fussy about advancing in a disorderly swarm) or they could have attempted to assemble a rearguard while the bulk of the column departed to aid the Spartans.  Neither of these things happened.  The Athenians were able to form up quickly enough to fend off their attackers, which precludes their having been in a long, thin column of march, and were unable to send the Spartans any assistance, which means their foes were able to assemble quite quickly, too.

who said anything about a 'long thin column of march'
Advancing in an eight wide column across a battlefield was standard enough procedure because you could just bring the column round 90 degrees and you're in line of battle
So as I said, it shows nothing about troops shambling about like locusts on a broad front. The Persians too might have deployed into a line of battle, advanced rapidly and lost formation but this is on a battlefield.

[Jim Webster]

Any army marching and being harassed by cavalry stays in a tight column, probably on a frontage of ten to eight wide, because then you're in line of battle if you turn 90 degrees.

The problem with this comment is that when the Greeks moved out they were not being harassed by cavalry, nor did they expect to be (if they had expected it, Pausanias would have called over the Athenians a lot sooner).

We're not talking about the Spartans, we're talking about the minor states, other than the Athenians and Spartans. They had been harassed, the harassing had stopped but they could expect it to restart at any time.
Nowhere does it say they adopted the 'Persian locust' formation and just sprawled across the countryside with no formation whatsoever

[Jim Webster]

The big hang-up seems to be moving the army.  Because we cannot think of methods which satisfy everyone we seem to be adopting a dog-in-the-manger attitude and assuming it could not be done.  We seem incapable of allowing for the possibility that people with a lot more experience of moving large Achaemeneid armies than ourselves might have thought of and implemented methods beyond our ken.

your case seems to be based on the fact that apparently the Achaemeneids developed techniques for moving huge armies that they forgot (because they never achieved it again) and that the rest of the world forgot (because nobody else attempted to do it either)

There were two thousand years of people moving armies after the Achaemeneids forgot their marvelous techniques and until the advent of the railway nobody tried moving six million men in a compact theatre of war like that.

[Jim Webster]

So far in this thread we have seemingly grudgingly accepted that naval supply is possible, that storing up the necessary grain is possible, 

You might have accepted that it's possible to store wheat for four years without modern technology (when we still don't store wheat for that length of time if we can help it) but please don't assume that other people have

[Dave Beatty]

Wow. 34 pages! Impressive.

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"?

Also, I recall reading in some ancient primary source (Herodotus?) that the Persians had to leave Macedonia because they ran out of food and fodder...

Cheers,

[Justin Swanton]

Weighing up the on-road vs off-road systems of march, which seems the most likely?

For on-road one assumes the Persian army could have marched probably 4 abreast at best on tracks designed for carts, and probably 2 abreast on other tracks. Given that most scholars allow at least 200 000 men for the army, could it have marched in this fashion from the Hellespont to Greece? Either a) it marches entirely on a single track in separate corps (at least 6 or 7) that move and camp separately, or b) it marches along 6 or 7 different tracks, occasionally meeting at a common campsite where the tracks converge (how often would that happen?).

Is a) feasible? (I start thinking of poo and related difficulties). This option means that the Greeks could ambush a single corps of the army without the other corps being able to come to the rescue, and it would take about a week for the entire army to concentrate. Option b) also allows corps to be ambushed and in this case it is even more difficult for the other corps to come to the rescue. This option also supposes an extensive network of tracks heading in the desired direction.

For off-road the Persians are required to clear a path many yards wide from the Hellespont to southern Macedonia, and probably across Asia Minor as well. Could they have achieved this in a 4 year period? How long does it take to clear land, leaving the odd boulder and large tree in place? They succeeded in clearing the battlefield at Gaugamela in presumably a few days at most - how does that compare?

[Patrick Waterson]

  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.

[Jim Webster]

Weighing up the on-road vs off-road systems of march, which seems the most likely?

For on-road one assumes the Persian army could have marched probably 4 abreast at best on tracks designed for carts, and probably 2 abreast on other tracks. Given that most scholars allow at least 200 000 men for the army, could it have marched in this fashion from the Hellespont to Greece? Either a) it marches entirely on a single track in separate corps (at least 6 or 7) that move and camp separately, or b) it marches along 6 or 7 different tracks, occasionally meeting at a common campsite where the tracks converge (how often would that happen?).

Actually the Persians could have dealt with this by throwing a cavalry screen forward to the passes where Macedonia meets Thessaly to avoid the risk of unexpected infantry attack. Their fleet should have been able to screen their flank
There's obviously the risk of local treachery, but each corps marching in decent military order was probably enough to cope with that.
Actually the way I mentioned it, a corps on the march would have a minimum of two other corps within two miles of it, and the system allows everybody clean camping and fresh forage to collect