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

[Jim Webster]

Perhaps then you can give us an example of a regular army that put 1.8 million men, plus perhaps two or three times that number of camp followers plus however many hundreds of thousands of head of livestock across a single bridge in a seven day period?

Two bridges, be fair - one for the 1.8 million men, the other for the camp followers, livestock, etc. 50% less impossible 

Having spent a lifetime working with livestock I suspect I'm one of the few society members who has had to deal with 230 tons fecal matter.
I remember explaining to somebody just how you had to use a tractor mounted stirrer to break the crust on a slurry pit and get it properly stirred up.
As I was telling him what sounds to listen out for, I realised I have an awfully specialist skill set, some of which is probably nontransferable 

[Erpingham]

I love the matter-of-fact tone of this

A 1,000 pound horse will defecate approximately four to thirteen times each day and produce approximately nine tons of manure per year. The 1,000 pound horse will produce, on the average, 37 pounds of feces and 2.4 gallons of urine daily, which totals about 50 pounds of raw waste per day in feces and urine combined.

These are modern US figures but I doubt horse biology has changed that much. 

[Andreas Johansson]

I love the matter-of-fact tone of this

A 1,000 pound horse will defecate approximately four to thirteen times each day and produce approximately nine tons of manure per year. The 1,000 pound horse will produce, on the average, 37 pounds of feces and 2.4 gallons of urine daily, which totals about 50 pounds of raw waste per day in feces and urine combined.

These are modern US figures but I doubt horse biology has changed that much.

Presumably Achaemenid horses were a bit smaller and produced a bit less waste. I find myself wondering if smaller horses makes for a better or worse carrying capacity / waste production ratio ...

[Erpingham]

I love the matter-of-fact tone of this

A 1,000 pound horse will defecate approximately four to thirteen times each day and produce approximately nine tons of manure per year. The 1,000 pound horse will produce, on the average, 37 pounds of feces and 2.4 gallons of urine daily, which totals about 50 pounds of raw waste per day in feces and urine combined.

These are modern US figures but I doubt horse biology has changed that much.

Presumably Achaemenid horses were a bit smaller and produced a bit less waste. I find myself wondering if smaller horses makes for a better or worse carrying capacity / waste production ratio ...

Not necessarily.  According to modern figures on the internet, a 1000lb/450 kg horse would be between 14-15 hands.  Not a big horse.  But I don't know how big Persian cavalry horses were.

[Duncan Head]

According to modern figures on the internet, a 1000lb/450 kg horse would be between 14-15 hands.  Not a big horse.  But I don't know how big Persian cavalry horses were.

Estimates vary. One is:

Les Néséens devaientmesurer au moins 148 cm pour un poids minimum de 380 kg.

The various non-Nisaeans in the force might be smaller.

[Erpingham]

Perhaps then you can give us an example of a regular army that put 1.8 million men, plus perhaps two or three times that number of camp followers plus however many hundreds of thousands of head of livestock across a single bridge in a seven day period?

According to this site, Napoleon managed to cross a force of 120,000 across the Nieman in a day.  He had three bridges and they were shorter but probably narrower.  Obviously, not strictly compatable but shows the scale of efficiency superiority the Persians need to have over more modern forces to sustain the "mega-army" thesis.

[Justin Swanton]

Perhaps then you can give us an example of a regular army that put 1.8 million men, plus perhaps two or three times that number of camp followers plus however many hundreds of thousands of head of livestock across a single bridge in a seven day period?

According to this site, Napoleon managed to cross a force of 120,000 across the Nieman in a day.  He had three bridges and they were shorter but probably narrower.  Obviously, not strictly compatable but shows the scale of efficiency superiority the Persians need to have over more modern forces to sustain the "mega-army" thesis.

The article doesn't actually state how long it took for the 120 000 men to cross the Niemen, just that they used three pontoon bridges and were reviewed by Napoleon as they crossed. That suggests that it was a daylight operation. If they were split into 3 groups each with 40 000 men and marched 4 men wide, and each man occupied an intermediate order space of 1 square yard, their columns would be 10 000 yards long which implies that marching at 4km/h they could clear the bridges in less than 3 hours.

So let's do some more sums. 40 000 men marching 4 wide cross a narrow bridge in 3 hours. Assume a bridge somewhat less wide than a trireme's length - say 30 yards. The men march in a column 30 men wide. Let's make it 20 men wide. 40 000 men will pass a given point on the bridge after half an hour. In a 24hr day 1 920 000 men will cross the bridge. In 7 days 13 440 000 will cross it. One can only conclude the Persians were remarkably inefficient about the exercise.

[Andreas Johansson]

Talking of pdfs, and remembering the need to introduce novelty, have we had this article before?  A warning though - it is scanned upside downand backwards.  You will need to print and reassemble it.

Many pdf readers can helpfully rotate the view for you

But strangely couldn't in this case.  They also can't reverse the page order (unless you have the expensive paid-for ones)

Happily, my employers have blessed me with a pdf editor of such surpassing powers that I can rotate the pages even in this case. Anyone wanting a correctly oriented copy can drop me an email at the aforementioned address: andreasj at gmail dot com

(No promises re page order: the original file shows as in the right order to me, so I can't tell if whatever made them show up in the wrong one for you will be fixed in my file.)

[Erpingham]

Perhaps then you can give us an example of a regular army that put 1.8 million men, plus perhaps two or three times that number of camp followers plus however many hundreds of thousands of head of livestock across a single bridge in a seven day period?

According to this site, Napoleon managed to cross a force of 120,000 across the Nieman in a day.  He had three bridges and they were shorter but probably narrower.  Obviously, not strictly compatable but shows the scale of efficiency superiority the Persians need to have over more modern forces to sustain the "mega-army" thesis.

The article doesn't actually state how long it took for the 120 000 men to cross the Niemen, just that they used three pontoon bridges and were reviewed by Napoleon as they crossed.

"The invasion commenced on June 24, 1812. ..... The center of mass of French forces focused on Kovno and the crossings were made by the French Guard, I, II, and III corps amounting to some 120,000 at this point of crossing alone. The actual crossings were made in the area of Alexioten where three pontoon bridges were constructed. The sites had been selected by Napoleon in person. Napoleon had a tent raised and he watched and reviewed troops as they crossed the Niemen."

"June 25 found Napoleon's group past the bridge head with Ney's command approaching the existing crossings at Alexioten."

Napoleon's group is the one that crossed at Alexioten.  One day after starting, they are on the other side of the river.  Ergo, it took them a day to form up, cross, reform and move out beyond the bridgehead.  However, I know very little about Napoleonics and it may be that less than 120,000 crossed on that first day.  I can't see it being more from the text given.  It is possible they didn't get all their logistic train across, based on

"They were plagued from the outset as logistics trains simply could not keep up with the forced marches of the corps and rear formations always suffered the worst privations."

So let's do some more sums.

We have a lot of sums but we tend to disagree whether they mean much.  To me, the sums we have add up to the impossibility of taking Herodotus literally.  To others, they show how plausible the literal interpretation is.  Perhaps stepping back and placing the action in the continuum of known military capacity would be more fruitful? What sorts of sizes of expeditionary forces using naval logistics and similar technological level are we aware of?

[Justin Swanton]

"The invasion commenced on June 24, 1812. ..... The center of mass of French forces focused on Kovno and the crossings were made by the French Guard, I, II, and III corps amounting to some 120,000 at this point of crossing alone. The actual crossings were made in the area of Alexioten where three pontoon bridges were constructed. The sites had been selected by Napoleon in person. Napoleon had a tent raised and he watched and reviewed troops as they crossed the Niemen."

If the invasion started on June 24th then one needs to factor in the time to construct the pontoon bridges as that would mean troops crossing over to the Russian side of the Niemen. The Nieman at the point of invasion is about 100m wide. Building three pontoon bridges capable of carrying not only men but also horses, cannons and wagons, would have taken some time. That leaves not so many daylight hours for the men to cross, and, looking the numbers (and numbers do mean something) the men needed only a few hours anyway.

We have a lot of sums but we tend to disagree whether they mean much.  To me, the sums we have add up to the impossibility of taking Herodotus literally.

How so?

[Erpingham]

If the invasion started on June 24th then one needs to factor in the time to construct the pontoon bridges as that would mean troops crossing over to the Russian side of the Niemen. The Nieman at the point of invasion is about 100m wide. Building three pontoon bridges capable of carrying not only men but also horses, cannons and wagons, would have taken some time.

I have to confess I'd assumed the bridges were constructed prior to the start of the advance.  To do otherwise would be a bit of an "It's a Knockout" sort of competition, wouldn't it?

That leaves not so many daylight hours for the men to cross, and, looking the numbers (and numbers do mean something) the men needed only a few hours anyway.

I think this reflects the difference between us.  To me, if 100,000 took a day to cross a river, there was a practical reason for that.  Plenty of opportunity for "Hurry up and wait" , for example, and many small things that add up to the friction of a military operation (yes, I know you don't believe in friction, but Clausewitz actually fought in this campaign).  I don't think we are dealing with a three continuous streams of 37,000 close packed troops, so paper calculations of how long they would take to pass a bridge at a constant speed are a bit irrelevant to me.

We have a lot of sums but we tend to disagree whether they mean much.  To me, the sums we have add up to the impossibility of taking Herodotus literally.

How so?

I'd be in danger of breaking the 1000 repeats rule   Put simply, I put a much greater weight on the problems of logistics, particularly issues like "over the beach" supply with small ships, the small buffer that a maximum one week supply baggage train gives when operating at the end of a long nautical supply chain, the capacity of that supply chain to actually deliver given the technology and the variable weather, the viability of marching in dense blocks nose to tail for 15km a day through basically unprepared ground churned up and defecated on, whether they really could find fuel for and prepare food for that large a number, water management, feeding the animals and keeping them fit.  There are other issues around failure to look at sources critically and the perspective of other examples in military history.  Is that enough?

[Jim Webster]

I'd be in danger of breaking the 1000 repeats rule   Put simply, I put a much greater weight on the problems of logistics, particularly issues like "over the beach" supply with small ships, the small buffer than a maximum one week supply baggage train gives when operating at the end of a long nautical supply chain, the capacity of that supply chain to actually deliver given the technology and the variable weather, the viability of marching in dense blocks nose to tail for 15km a day through basically unprepared ground churned up and defecated on, whether they really could find fuel for and prepare food for that large a number, water management, feading the animals and keeping them fit.  There are other issues around failure to look at sources critically and the perspective of other examples in military history.  Is that enough?

it is for me 

[Justin Swanton]

Put simply, I put a much greater weight on the problems of logistics, particularly issues like "over the beach" supply with small ships, the small buffer that a maximum one week supply baggage train gives when operating at the end of a long nautical supply chain, the capacity of that supply chain to actually deliver given the technology and the variable weather, the viability of marching in dense blocks nose to tail for 15km a day through basically unprepared ground churned up and defecated on, whether they really could find fuel for and prepare food for that large a number, water management, feeding the animals and keeping them fit.  There are other issues around failure to look at sources critically and the perspective of other examples in military history.  Is that enough?

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. One day, possibly two days, would be enough to get the entire army across the Hellespont, and seven days are allotted to the operation. Friction is factored in. So one needs some other obstacle. Thus far the main potential obstacles brought forward are:

1. Not enough food or water.

Not conclusively proven. All the concrete evidence thus far says there was enough of both. The fleet was large enough, the time to gather the food long enough. This leads to the next argument:

2. The food will rot.

The entire economy of Antiquity was substantially built around growing, storing and moving grain. Grain is harvested only once a year, perhaps twice in some areas. Hence it has to last up to 12 months to the next harvest. It also has to be moved sometimes considerable distances to the larger urban areas and - this point is important - it has to last long enough to supply an army on campaign no matter how large or small that army is. If the Achaemenids could do it for 200 000 men they could do it for 2 000 000.

3. Too much poo.

The most frequent objection in this thread (!). It forgets that 3 400 000 men and 80 000 horses et al don't all march along the same three-yard-wide track.

4. Roads too few and narrow.

Irrelevant if one posits the army didn't use roads.

5. Stuff and nonsense.

Yep.

6. Lettered academics don't agree.

Yep.

7. Patrick said it.

Yep (couldn't resist including this one. I did try).

[Jim Webster]

The entire economy of Antiquity was substantially built around growing, storing and moving grain. Grain is harvested only once a year, perhaps twice in some areas. Hence it has to last up to 12 months to the next harvest.

Storing grain for the rest of the year to the next harvest was possible with a little care.
The problem is people talking of stockpiling it for several years. That is an entirely different issue

This is symptomatic of the debate. Hard questions are answered with vague answers like "The most frequent objection in this thread (!). It forgets that 3 400 000 and 80 000 horses et al don't all march along the same three-yard-wide track."
Strangely enough I'd realised that, but given the terrain, and the choke points, for example the Bosporus, or when the army gathered at Thermopylae vague assertions that the army split into separate columns don't cut the mustard

[Erpingham]

Thus far the main potential obstacles brought forward are:

You decided to ignore mine then ?

Trying to avoid tit for tat (what are we, diplomats?) but

Not enough food or water.
It's not just about paper calculations of quantities, its about stuff like supply chains, distribution, water management, food preparation, transporting fodder (its very bulky for its weight).  I won't repeat again.

Too much poo.

Like a mighty army
Moves the Persian host;
Brothers, we are treading
Where the horse have trod.

Apologies to Sabine Baring-Gould

Roads too few and narrow.
Has anyone raised this? 

Lettered academics don't agree.
Nor do professional soldiers.  If you think such persons are always wrong, this is fuel to your argument.  If you think they usually have a point, it's evidence in the other direction.  This is one of those meta-questions about how we view historical events on this forum, which is fundamental to many of our disputes.
     
Patrick said it.
It's not Patrick saying it per se, more his approach to history is unorthodox and leads to clashes with the more orthodox majority. Again a meta-issue, not confined to this subject.