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

[Jim Webster]

Take imperial Rome. The city needed 420 000 tonnes of grain brought by ship each year. If the average Roman merchant ship had a carrying capacity of 100 tons that means 4200 ship voyages to feed the city. It takes two days by sea from Carthage to Rome with a favourable wind and four days with an unfavourable one, so a round trip including loading time, repairs and so on probably took about 10 days. The Mediterranean was navigable for 8 months of the year so a ship could make the trip about 24 times at best which means at least 175 ships dedicated just to bringing grain to Rome, year after year. But the Roman Empire did it, free of charge. What is the big obstacle for the Persian Empire doing it as a once-off, with years of preparation beforehand?

strangely enough, the city of Rome didn't move about. It had taken centuries to get the infrastructure right

Are beaches an insuperable problem?

Galleys were designed to be pulled up onto them
Merchant ships weren't

[Jim Webster]

I'm not sure amphorae would actually be necessary. One needs to keep the grain dry below decks for a few days during the ship's passage across the Aegean. At the print shop where I work, the floor is regularly flooded after a heavy rain. Water and paper make a bad combination, so we keep all paper on palettes. Problem solved. It's enough to ensure the sacks don't touch the bottom or sides of the ship's hull. The Romans solved the problem putting an inner layer of planks over the ship's ribbing, on which the grain sacks were stored. One imagines the Persians had a similar solution.

The problem isn't so much wet (which obviously is to be avoided) as humidity. If the grain moisture rises from 14% to 15% you have serious problems.
Dry grain (14%) will absorb moisture out of the air
Sea air does have more moisture so the sea is a bigger risk
The importance of sacks in the advantage I gave was that it does give the air chance to circulate on dry days and hopefully bring the moisture down again

[Patrick Waterson]

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.

Presumably that would  apply to every other invasion they launched including the one that led to  Marathon.?

It did seem to be the prevailing mentality.  The force which set out on the Marathon is noted as being a "numerous and well-appointed land army" (Herodotus VI.95)  The force Darius led against the Scythians is recorded as being 700,000 men (Herodotus IV.87) and vast armies were an Achamenid trade mark until 334 BC when Memnon appears to have sent home the Achaemenid levies in his army prior to the Granicus.  Darius III Codomannus debated whether to take the traditional huge host to Issus or follow Charidemus' scheme of relying solely on a force of 30,000 Greeks and the best 70,000 the Persian Empire could muster; in the end (and after executing Charidemus for bad manners) he opted for both.  His swan song at Gaugamela saw the second largest recorded assemblage of Achamenid military manpower.

Xerxes' failure, however, did cause a rethink, which appears to have remained in limbo until after Cunaxa, when the quality and effectiveness of Greeks became apparent.  Thereafter, Persian invasions of Egypt involved adding a cutting edge to the main army: 20,000 Greeks and 200,000 Asiatics (374-3 BC); 30,000 Greeks and 300,000 Asiatics (343 BC).  Each of these still had the characteristic years' long preparation period beforehand.

[Patrick Waterson]

Are beaches an insuperable problem?

Galleys were designed to be pulled up onto them
Merchant ships weren't

That was not the way you unloaded a classical merchant ship.  You swung the cargo onto lighters which ferried it to shore.  So no problem there (says the naval historian).

[Patrick Waterson]

Just a thought but what would be Herodotus' source for this quote from Xerxes?

Quite possibly Demaratus himself.  Herodotus did quite a bit of travelling and interviewing, and I think Demaratus was one of his subjects.  Demaratus might have inserted a bit of after-the-event improved repartee for his own contribution (or he might not), but I think he would have recounted Xerxes' remarks accurately enough.  He had cause to remember them at the time.

[Justin Swanton]

No no Justin, you just cannot go equating all statements in an ancient source as having the same value.
If we took accounts of WW2 a contemporary souce of the Battle of Britain could give excellent information on the types and capabilities of the aircraft, worse qualuty of information on the numbers taking part, poor information on the effects of the bombing and even worse on the numbers shot down. The source of the information might be someone in the propaganda dept of one of the combatants, German, British or Italian and have an ulterior motive to increase or decrease numbers.

Depending on who is doing the talking I agree that one can get wildly inaccurate accounts of what happened during the Battle of Britain. However...

If 2000 years later someone was looking at the memoirs of an Italian pilot who took part, writing a report to his bosses and that was our only source then  should  the historians of the future just accept the numbers or that the CR42 was a good fighter because it had great visibility and a tight turning circle and coukd outfight a Gloster Gladiator. Of course someone could construct a logic that the Gladiator fought in the Battle of Britain because a few did, because the RAF clearly had them, because one was dug up in Iraq or Egypt and dated to 1941.

An Italian pilot, writing anecdotally about his experiences in England, is not on the same level as historians like Herodotus, Arrian, Polybios, Livy, et al. who are trying to write history and hence to get their facts right. They are not bureaucrats in a dictatorship or functionaries in a Ministry of Propaganda. They would use a lot of sources and sift their reliability before committing pen to paper. Putting them on the same level as an anecdotal pilot unfairly diminishes their competence IMHO.

Ancient sources need to be looked at in their own context and understood for their own motivations. If later armies all seem to be smaller, far smaller and yet be the product of states that we know to have the economic power to support an army equal to any Persian then it is extremely unlikely that Persia deployed forces that were much greater in size.

Unless the military doctrine of the Persians and their predecessors set a great store by size which the Greeks and their successors did not.

In theiry Rome in the Late Empure could provide 650, 000 troops ( I think that's Agathias) so why do they not put out armies of halh a million? Well they have frontiers to defend, internal security to attend to and the ligisics would have been a nightmare.

Rome followed the same military tradition of Macedonia and to a lesser extent Greece of creating smaller but well-trained and well-armed armies rather than huge forces most of which were untrained and poorly-armed levies who where there just to impress the enemy without actually fighting him. Once Greece and Macedonia called Persia's bluff it was game over for big armies.

Please don't give comparative numbers from the Bible....its just not that sort of historical document.

Although it's used as such. But fine, we'll leave it alone.

The Greeks had a very good motive for consistently exaggerating the size of Persian armies. As had Caesar for exaggerating the numbers of Gauls or Tacitus for bigging up the numbers of Ancient Brits.

Or the Gauls and Britons had a military tradition of every able-bodied man going off to war when the need arose. Unlike the Romans they didn't have professional standing armies.

The Greeks  were beating the Persians, but at the same time had a poor opinion of Persian organisation, motivation, equipment, morale...the lot. How could an army of such people be terrifying enough to be an heroic opponent...why, by giving them huge numbers of slave soldiers, formidable by their mere mass, despicable in equipment and freedom.

Such a huge army would just starve when the Greeks took control of the seas.

It did starve, but it wasn't part of Xerxes' plans for the Greeks to take control of the seas.

It would be effectively immobilised by the problems of food distribution.

How so?

[Erpingham]

If we insist on pursuing Roman parallels, this is quite interesting.  This reckons the Isis at 1200 tonnes (though I'm not sure that is capacity rather than displacement).  Key things to remember is that these big ships didn't exist earlier and even to the Romans they were rare.  They also needed deep water port facilities.

[Jim Webster]

Are beaches an insuperable problem?

Galleys were designed to be pulled up onto them
Merchant ships weren't

That was not the way you unloaded a classical merchant ship.  You swung the cargo onto lighters which ferried it to shore.  So no problem there (says the naval historian).

which was such an amazingly effective and efficient system that people abandoned the whole old fashioned idea of investing a lot of capital in harbour facilities and just unloaded across the beach

[Erpingham]

That was not the way you unloaded a classical merchant ship.  You swung the cargo onto lighters which ferried it to shore.  So no problem there (says the naval historian).

Are you sure about that?  Lighters are usually associated with infrastructure of permanent ports. 

[Patrick Waterson]

Peter Green (the historian, not the guitarist) in his Greco-Persian Wars page 62 gives some of them for this particular instance (basically, Xerxes had every reason to exaggerate the numbers, while the Greeks after they won had no reason to revise them downwards, and that the numbers were for before the entrance into Europe).

Just to play the man not the ball here, Phil Sabin was wholly unimpressed with Peter Green's conclusions about the Granicus.  Are you sure you really want to rely on Peter Green for anything, particularly when the conclusions amount to little more than a recitation of Peter Green's opinions?

Thus far in this thread I haven't seen any killer argument - backed up with proof - that demonstrates the impossibility of such an enormous army marching, camping and being fed and watered from the Hellespont to Greece.

You probably have, but choose not to see it as such

Although to be fair Aaron does not point to anything that might be considered as such.

Notes to the Landmark Herodotus (p.577) translating Herodotus' grain figures into modern quantities indicate the army required 4,700 tons per day (470,000 for 100 days; 1,715,500 for a year). These supplies are coming through beaches, in potentially unfriendly territory, and without dedicated unloading crews at the drop off point, and without troops in place to secure depots in advance (if advance depots is part of the argument) so it doesn't really compare to Imperial Rome's 420,000 tons coming through a purpose-built port with organized shipping and regular crews at both ends.

Couple of assumptions here:
1) potentially unfriendly territory
Prior to Thermopylae, the only unfriendlies were the mauntain lions who attacked baggage animals (with a distinct preference for camels).  The presence of a 1.7 million strong army had already made the relevant areas friendly; Thracians and Greeks were rushing to join Xerxes; local Greek cities were supplying his army (Herodotus VII.118-119).
2) without troops in place to secure depots in advance
Up to Acanthus, the local populations secured 'depots'.  At Thermopylae, the army and fleet looked after their own security.
3) a purpose-built port with organized shipping and regular crews at both ends
The only real difference is the lack of a purpose-built port at one end.  I hope nobody would be so uncharitable as to suggest that Phoenicians and the like were unpractised at unloading ships over beaches, because this is how they conducted most of their trade.

There is also the issue of choke points as mentioned by pretty much everyone. H 7.176 mentions the route narrowing to a space the width of a wagon in two places. Try getting 1,700,000 fighting men let alone the other 3.5M plus  followers, cavalry horses, baggage animals, food on the hoof, and baggage carts through spaces that narrow in timely fashion!

Or, to give it its more commonly known name, Thermopylae.  Once the Persians had cleared away the Greek defenders, they did not all go through it, but went round it, campaigning against the Phocians en route (Herodotus VIII.30-34).

There are of course other objections too, but one that I don't think has been noted in this thread so far is the 'shock and awe factor' that 10 white horses, a chariot, 10 more white horses, 1000 picked cavalrymen, 1000 picked foot, and the 10,000 Immortals elicits in 7.40-41 & 7.55. If the army was really 1,700,000 strong, would so much be made of these comparatively small elite contingents?

Very much so, because they are the 'bravery' part of the Persian 'bravery and numbers' equation.  In any event, in the passages quoted their effect is spectacular display; they do not seem to be shocking anyone, although they would be very useful for aweing the contingents from the further-flung reaches of the Empire.

[Erpingham]

Just to play the man not the ball here, Phil Sabin was wholly unimpressed with Peter Green's conclusions about the Granicus.  Are you sure you really want to rely on Peter Green for anything, particularly when the conclusions amount to little more than a recitation of Peter Green's opinions?

So, just checking.  Because Phil Sabin was unimpressed with Peter Green's views on a battle in another campaign altogether, his opinions about the grand strategy in another time and place can simply be dismissed?

[Patrick Waterson]

Key things to remember is that these big ships didn't exist earlier ...

They were specialised for optimisation in a specific role, but arguing from form to function (or perhaps vice versa) there is no reason large grain ships could not have existed earlier, when bulk grain transportation at the behest of national and/or imperial authorities seems to have taken place.

That was not the way you unloaded a classical merchant ship.  You swung the cargo onto lighters which ferried it to shore.  So no problem there (says the naval historian).

which was such an amazingly effective and efficient system that people abandoned the whole old fashioned idea of investing a lot of capital in harbour facilities and just unloaded across the beach

Much of Phoenician trade was conducted on the basis of transferring cargo to shore, waiting until the locals had piled up goods of sufficient value, then loading the pile of goods and going back home.  This took place across beaches and without a port.  The Vikings would later use a very similar system.

Military operations also took place where on occasion people had inconveniently omitted to build ports.  Standard procedure for anyone with any sort of experience was: supplies into boats; boats onto shore; supplies out of boats; boats back to ship for next instalment.

This is of course very crew-intensive.  Merchant crews much preferred letting someone else do much of the work in the comfort of a port.  Ports are also very useful for overhauling ships; they are just not 100% vital for unloading supplies.

That was not the way you unloaded a classical merchant ship.  You swung the cargo onto lighters which ferried it to shore.  So no problem there (says the naval historian).

Are you sure about that?  Lighters are usually associated with infrastructure of permanent ports. 

Which means that borrowing them for a campaign is no problem, as they are already in existence.

The question of weather is worth picking up.  As has been mentioned (I believe by Anthony), even a light swell can interfere with unloading.  Mediterranean weather, however, tended to be of two varieties - very good or very bad -  with very little in between.  Unless the weather was so bad as to imperil your ships, it tended to be good enough for unloading.

[Patrick Waterson]

Just to play the man not the ball here, Phil Sabin was wholly unimpressed with Peter Green's conclusions about the Granicus.  Are you sure you really want to rely on Peter Green for anything, particularly when the conclusions amount to little more than a recitation of Peter Green's opinions?

So, just checking.  Because Phil Sabin was unimpressed with Peter Green's views on a battle in another campaign altogether, his opinions about the grand strategy in another time and place can simply be dismissed?

Isn't that the approach commonly advocated here regarding Herodotus?

[Justin Swanton]

Are beaches an insuperable problem?

Galleys were designed to be pulled up onto them
Merchant ships weren't

That was not the way you unloaded a classical merchant ship.  You swung the cargo onto lighters which ferried it to shore.  So no problem there (says the naval historian).

which was such an amazingly effective and efficient system that people abandoned the whole old fashioned idea of investing a lot of capital in harbour facilities and just unloaded across the beach

Harbours make unloading of cargo somewhat easier but more importantly they are a safe refuge for ships in bad weather, and no matter what the weather if a ship can make it to a harbour it can load/unload its cargo.

[Flaminpig0]

Just a thought but what would be Herodotus' source for this quote from Xerxes?

Quite possibly Demaratus himself.  Herodotus did quite a bit of travelling and interviewing, and I think Demaratus was one of his subjects.  Demaratus might have inserted a bit of after-the-event improved repartee for his own contribution (or he might not), but I think he would have recounted Xerxes' remarks accurately enough.  He had cause to remember them at the time.

I tend to go with the idea that  ancient historians are not equivalent to modern practitioners  in terms of commitment to accuracy, attributing sources or even having a similar idea to what  constitutes truth and that they were more than capable of creating  speeches  to more effectively  convey a point to their audience.  However,  in this case I suspect that Herodotus would have attributed Demaratus if that is where he had got the quote from.