Army living off the land

johnincornwall

Ad Honorem
Nov 2010
7,813
Cornwall
What is the typical and/or maximum size of an army that can live off the land, that is, does not rely on supply lines? If memory serves me right, Roman legions of Principate might have been sized based on that concern, but I am not 100% certain of that one. I do know that an army 100 000 strong would require sophisticated logistical system in place; IIRC, Byzantines set up such systems for field armies 20 000 or so strong.
In the central lands of Iberia - very few. You couldn't. No farmers, not much grass, not much water, a few fortified towns you couldn't get in. Bye bye.

I sort of worry you are playing war games in your head and don't really conceive what 100,000 people in the same place looks like, what it needs, what it does. How many latrines they need, how much food, how much grass horses eat (they can't stand still). If any large figures are reliable you can bet your boots they were well spread out. Charlemagne's unsuccesful invasion of Spain was split into 2 columns for this reason. Napoleon's ultimately unsuccessful logistical operation in Russia was split into XII (?) corps. If you followed the line of a different Corps you wouldn't eat.

Just look at a 100,000 crowd in a football stadium and imagine them sat in your village. How long would your eggs last? :)
 
Oct 2011
487
Croatia
In the central lands of Iberia - very few. You couldn't. No farmers, not much grass, not much water, a few fortified towns you couldn't get in. Bye bye.

I sort of worry you are playing war games in your head and don't really conceive what 100,000 people in the same place looks like, what it needs, what it does. How many latrines they need, how much food, how much grass horses eat (they can't stand still). If any large figures are reliable you can bet your boots they were well spread out. Charlemagne's unsuccesful invasion of Spain was split into 2 columns for this reason. Napoleon's ultimately unsuccessful logistical operation in Russia was split into XII (?) corps. If you followed the line of a different Corps you wouldn't eat.

Just look at a 100,000 crowd in a football stadium and imagine them sat in your village. How long would your eggs last? :)
The reason I am asking is precisely because I know how large an army of 100 000 is. Hell, I've been calculating logistics for a 15 000 strong Byzantine-style army, and numbers are... well. Although much of that is fodder for horses; an all-infantry army could afford to be much larger. Yet such armies were, at least in the antiquity, deployed semi-routinely (if you believe the sources). At Cannae, Romans deployed cca 80 000 troops. At Plateia, both sides had around 80 000. But for a time, during Middle Ages, battle get much smaller - even for highly organized polities such as surviving Roman Empire. At Yarmouk, both sides had cca 20 000, yet the Orient (Levant) was lost as a result. At Chandax in 960, after Roman Empire had recovered, both sides had cca 40 000. Arcadiopolis, 970, both sides had cca 10 000, with Bulgar-Rus army potentially up to 30 000.

As I noted before, I read somewhere (can't remember where) that Roman legion was sized to, approximately, maximum size of a unit that could live off the land on campaign (in for-a-time-typical Western European conditions) and still maintain cohesion.
 
Mar 2018
870
UK
As I noted before, I read somewhere (can't remember where) that Roman legion was sized to, approximately, maximum size of a unit that could live off the land on campaign (in for-a-time-typical Western European conditions) and still maintain cohesion.
The point everyone is trying to make is that there is really no such thing as typical. The variance between different places, time of year, conditions, etc... is orders of magnitude larger than the average. This makes the average basically meaningless.

What would be meaningful, however, would be to ask something more along the lines of "How big can an army be such that, 90% of the time, in this region, during the campaigning season, in the face of a known strength of opposition, getting supplies from the land wouldn't be too difficult?"
 
Oct 2011
487
Croatia
The point everyone is trying to make is that there is really no such thing as typical. The variance between different places, time of year, conditions, etc... is orders of magnitude larger than the average. This makes the average basically meaningless.

What would be meaningful, however, would be to ask something more along the lines of "How big can an army be such that, 90% of the time, in this region, during the campaigning season, in the face of a known strength of opposition, getting supplies from the land wouldn't be too difficult?"
You are adding complications where there are none, I think. I do not think terrain is much different between various places in Apenine pennisula in, say, 100 BC, and campaigns were typically during late summer or autumn IIRC. That eliminates a lot of variation.
 

sparky

Ad Honorem
Jan 2017
5,257
Sydney
" Napoleon's ultimately unsuccessful logistical operation in Russia was split into XII (?) corps. If you followed the line of a different Corps you wouldn't eat. "

After the battle of Maloyaroslavets Napoleon intent to use a southern route was foiled
he was forced to go back by the same road he came in

it had been thoroughly devastated during the summer by the Russian army falling back then the Grande Armee advancing
the horses were starving , the foragers were hounded by cossacks and had to stay close to the columns
the troops at the front could scratch a meager living but the tail had absolutely nothing left
then the snows came impeding movement further , there were case of cannibalism
 
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Oct 2015
935
Virginia
As everybody says the variables are so great as to make any answer problematic.

But (!) In May 1863 General Grant marched ~44,000 men from Grand Gulf Mississippi to Jackson to Vicksburg (~100 mi) in about 20 days living mostly off the land.

In February 1864 General Sherman marched ~27,000 men from Vicksburg to Meridian Mississippi (~135 mi) and back in about a month.

In Nov-Dec 1864 Sherman marched ~62,000 men from Atlanta to Savannah (~300 mi) in about 40 days.

In Feb-Mar 1865 he took ~60,000 men from Savannah SC to Fayetteville NC, via Columbia SC (~300+mi) in about 40 days.

In each case Grant and Sherman marched against little or no opposition, in several columns of ~12-15,000 men, each column 10-15 miles apart with cavalry covering the front and flanks, and fed his men and animals almost totally by foraging.

That doesn't help much except maybe to indicate that in decent agricultural country a column of 12- 20,000 men with their animals can feed themselves locally if they keep moving.

I think Turenne said no army should be larger than 50,000, the Emperor Maurice (who operated in very different terrain) I think suggested 15-20,000. In any case, if an enemy is present and able to interfere with movement and foraging, total reliance on living off the land without some fallback to magazines or water transport is a recipe for disaster.
 
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Chlodio

Forum Staff
Aug 2016
4,630
Dispargum
In 1863, Lee fed 75,000 men for almost a month in the Shenandoah Valley, Maryland, and Pennsylvania, and this was in June and early July, the worst time of the year for finding food as the harvest of 1862 was mostly gone, but the harvest of 1863 had not yet begun. Not only did Lee feed his army, but he was able to send surplus supplies back to Virginia. This part of the US was unusually fertile.
 
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Oct 2015
935
Virginia
Even in high summer the Cumberland Valley, Adams and York Counties in PA are like gardens - one reason Lee went there. But that same September, the Army of the Cumberland nearly starved in Southeastern Tennessee. It all depends
 
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Oct 2011
487
Croatia
In each case Grant and Sherman marched against little or no opposition, in several columns of ~12-15,000 men, each column 10-15 miles apart with cavalry covering the front and flanks, and fed his men and animals almost totally by foraging.

That doesn't help much except maybe to indicate that in decent agricultural country a column of 12- 20,000 men with their animals can feed themselves locally if they keep moving.
Actually, that is at least part of an answer I was looking for. Thanks.
 
Oct 2015
935
Virginia
This is actually a question that has always bothered me as well, especially when sources talk about armies of 70 or 100,000 men in eras before railroads, steamboats, canals, army corps and professional staffs etc.
Have you looked at:
"Supplying War" - M van Creveld
"Alexander the Great and the Logistics of the Macedonian. Army"- D W Engels
"Logistics of the Roman Army at War"- J P Roth ?
They all give some interesting information, but there is not much discussion of the details of foraging on the march. Most surviving ancient sources show that able commanders like Caesar and Alexander always tried to send ahead to arrange for food and forage to be gathered before their armies marched thru a district, rather than relying exclusively on foraging.

It is also interesting that when Lee marched into MD in '62 and PA in '63 he moved in two or three separate columns covered on the flank by the cavalry, as did Bragg when he moved into KY in '62. 12 -25,000 seems to be about as many men as can conveniently move and forage in a single column - in country with a reasonable population density.
 
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