Celts - do you find it Gauling how rulesets treat them...

[Andreas Johansson]

I think that is now discredited Andreas ( That earlier farmers could not cope with heavy soils,) I read some time ago that the indicator of this, the Celtic field systems on  higher, lighter, chalky soils  only survive because they represent the farming of marginal land, by a larger population) and that the heavier soils  were farmed, but traces of that farming have been lost under subsequent tilling because the alluvial soils were richer and were in constant use from the iron age onwards.

I'm happy to believe the idea is outdated, but my inner pedant can't resist pointing out that farming heavy soils isn't quite the same as getting higher yields from them than from thinner Mediterranean ones.

[DougM]

The other point is while you may have a million men of fighting age capable of bearing arms, you simply cannot send everyone to fight, but more importantly, how do you concentrate them. So if we assume Gaul has 1 million available, (reduced because we're excluding the Province), slightly reduced again for the critical occupations that can't be spared for a general callout, the next step is? Sure, nominate a date and location, but if you're coming from the Atlantic Coast or the Ardenne, you have a long way to travel, you have to bring your own supplies, because wherever you go, the locals have taken it. If you can, carry 40 days of supplies, hope that the weather isn't too wet or too dry, that sources of water aren't polluted by large bodies of men travelling to the assembly point, your horses need to find grazing, that there isn't an outbreak of disease.

I'm more or less visualising that the percentage of men who could or would reach an assembly point is attenuated by distance, so you want it to be in as densely populated a region as you can find, healthy, away from mosquitos, plenty of grazing and fresh water, and then wait and see. As a commander, you would have to know how large a force was sustainable and for how long. After all, crops must be tended, harvests gathered, animals slaughtered for winter etc.

[Justin Swanton]

I think we did a study in the Persian logistics thread of how much food a wagon can carry and thus how many men it can feed and for how long. I'll try to dig it up.

[aligern]

We might usefully look at Doug's post in a bit more detail? The siege of Alesia takes place in September 52BC.  The grain harvest in France takes place in July and  August , so the harvest is in. Alternately one can probably ask the old, women and boys to get the crops in as they undoubtedly help anyway and so have the skills.
As to slaughtering animals for the winter etc. that is not a consideration for us in September.  The campaign is disruptive, but given  the constant raiding between tribes is disruptive.
As to how far the   recruitment  net can be cast, lets assume a 20 mile a day march ( long days in September) . and a six week campaign.  Two weeks to get there, two weeks to beat Caesar two weeks to get back.  Thats a radius of 300 miles , a circle of 600 miles diameter. Cavalry could come from further away . Its a huge recruitment area. We might also doubt that there are no supplies en route that can be purchased or gifted or even coerced.
Of course you are right that weather makes a difference, but its September, not February. Of course there will be didease, problems watering, clogged roads etc. , all the strategic friction that reduces armies, but the contingents are not marching through hostile territory .
Inthink the size ofbthe relief army is meant to be 250,000. Of course there is no easy cross check, but it does apoear feasible if the Gauls have a military system that can deliver in the proportions that Jim suggested that Southern Italy could.
😉 Roy

[Jim Webster]

I think we did a study in the Persian logistics thread of how much food a wagon can carry and thus how many men it can feed and for how long. I'll try to dig it up.

for wagons you need roads. Even after the Roman conquest the main arteries of commerce in Gaul were actually the rivers. The Rhone north and then short trips to get to the rivers flowing to the Atlantic
I have wondered whether Caesar's campaigns were linked to the rivers or not

[aligern]

You don't need roads as such.  Look at the performance of the Biers on the Great trek. You do do need hard flat ground which the Veldt has. In my recollection France has plenty of upland plateau, often with chalky soils that would be good for a wagon train. That said I suspect that the assembling army would use packhorses rather than wagons. Perhaps the wagons could follow up after the army had passed.
And yes, Jim you are right about Caesar and rivers. Isn't tgat why he is so keen to get to Vesontio?

Roy

[Erpingham]

The problem with river transport is you follow the rivers.  If you are concentrating people on a fixed point chosen for reasons other than its river links, you will have problems.

On wagons, Justin, you could try using Roman wagons as a basis (Celtic influence on Roman wheeled transport was significant) which would give you a heavy goods wagon around 1-1.5 tonnes capacity.  On the very rough basis of 1kg of cereals a day, that 1000-1500 person days.  For Roy's 250,000 strong army over 40 days, you'd need 6700-10000 carts.  Given they are advancing from many directions, they may be able to cut enough fodder as they march (with the usual caveats of time cost).  It is possible, using arrangements with tribes en route to provide some supplies, this number could be reduced.  Again, this is "order of magnitude" stuff, not an accurate assessment. 

[Justin Swanton]

You don't need roads as such.  Look at the performance of the Biers on the Great trek.

The Beers also had an impressive bottoms up performance, even naming their home-brewed Castle Lager after their well-known defensive formation. 

[Justin Swanton]

The problem with river transport is you follow the rivers.  If you are concentrating people on a fixed point chosen for reasons other than its river links, you will have problems.

On wagons, Justin, you could try using Roman wagons as a basis (Celtic influence on Roman wheeled transport was significant) which would give you a heavy goods wagon around 1-1.5 tonnes capacity.  On the very rough basis of 1kg of cereals a day, that 1000-1500 person days.  For Roy's 250,000 strong army over 40 days, you'd need 6700-10000 carts.  Given they are advancing from many directions, they may be able to cut enough fodder as they march (with the usual caveats of time cost).  It is possible, using arrangements with tribes en route to provide some supplies, this number could be reduced.  Again, this is "order of magnitude" stuff, not an accurate assessment.

Seems feasible. Again, I'm minded of Boudicca's wagon train that was so big it impeded the flight of her huge army.

Oh BTW, all hail the new Global Moderator!

[Erpingham]

Seems feasible. Again, I'm minded of Boudicca's wagon train that was so big it impeded the flight of her huge army.

Big wagon trains at the back of armies also feature a lot in Caesar.  The nature of these wagon trains might be explored by the Caesar experts but many seem to have many women and children.   This may distort appreciations of the size of forces

Oh BTW, all hail the new Global Moderator!

Sounds like something out of Star Trek   But then, moderator is one of those jobs even Daleks can do.  Mod-er-ate! Mod-er-ate!

[Imperial Dave]

Have we considered depots and caches of supplies? Presumably tribute in Gaul was collected for the tribal elite and so used for emergencies as well?

[DougM]

Is the 'national' leadership strong enough to impose the kind of discipline required for one tribe to create a cache for others? I don't know.

[aligern]

We should also consider that Vercingetorix had been operating a scorched earth policy wherever Caesar's army went.
I think Doug alluded to this.

Roy
Also to Andreas, Whatever soils the Gauls were using their population was probably a fifth or so of the popukation size at the maximum of unimproved agriculture. France has very productive soils and good clinate. That suggests tgat tge Gauls had plenty of choice of land for agriculture and would have used the best.  That is a good argument for tge use of fertile alluvium.
Roy

[Dangun]

On the very rough basis of 1kg of cereals a day, that 1000-1500 person days.  For Roy's 250,000 strong army over 40 days, you'd need 6700-10000 carts.  Given they are advancing from many directions, they may be able to cut enough fodder as they march (with the usual caveats of time cost).  It is possible, using arrangements with tribes en route to provide some supplies, this number could be reduced.  Again, this is "order of magnitude" stuff, not an accurate assessment.

I understand this wasn't the point of the post... but please forgive some satire.
10,000 carts Parkes arse to nose, would single file, be about 80km of baggage, and the troops would eat 12% of the supplies before the rear cart got to the front. God knows what the baggage animals would eat of the carts contents...

[Imperial Dave]

Is the 'national' leadership strong enough to impose the kind of discipline required for one tribe to create a cache for others? I don't know.

absolutely. If such cache's existed they would have been set up for local use but its surprising how persuasive 10000+ spears turning up on your door can be to share these especially when the alternative is Messer Caesar burning and looting the area anyway