Building fortifications the logistics

[Trethiwr]

Here's hoping this is the right place for this and I don't think it's been asked before.  

The legions famously built some incredible structures in their campaigns. I hadn't really grasped how incredible some of this stuff was until reading and writing about it. 

The "Masters of Rome" series, makes some of it more visceral, while non-fiction sources reaffirm how astonishing these engineering feats were. 

In particular, I am struggling to come to terms with the fortifications which were apparently built by Crassus to contain Spartacus.

If I have understood correctly, they built some sort of ditch and rampart across the toe of Italy (Calabria). I looked on Google maps and the distance looks to be around 50 miles. 

My back-of-the-envelope calculations suggest over half a million metric tonnes of soil would have needed shifting to make a ditch 12 feet deep and 6 feet wide and a corresponding rampart built from the spoils. 

Crassus had six or seven legions (I believe?) so up to 35,000 men? 

They would need to shift around 20 tonnes of earth each. And cut and bring timber to shore it up. 

Estimates based on answers on quora etc indicate this would have taken two weeks of solid back breaking graft. 

I think I know the answer to this, but, would they REALLY have done that?

Or did I get some sums wrong? Or did the wall not actually cut across the entire toe of Calabria but only encompass them in a town such as Rhegium? 

What am I missing? 

[Trethiwr]

On a related topic, I don't want to use the term "tonnes" in referring to the amount of earth to shift. 
I could refer to a number of talents, or is there a larger weight measure used by the Romans?  
 

[caldrail]

The abilities of ancient civilisations are quite stunning but then they didn't have the machinery we take for granted in this day and age to make our working lives easy. Even in the Victorian era, an Irish navvie working on a railway was expected to move twenty tons of 'muck' a day. Try it. You won't get close. Their diet was extraordinary, consisting of several meals a day with steak and lashings of beer.

The ancient Egyptians are a case in point. We often point to pyramids but they built other stuff too. Fort Buhen, now at the bottom of Lake Nasser since the sixties, had a circumference of more than a mile of thirty meter high walls and a dry moat. That's one substantial castle, even by medieval standards. Or perhaps Stonehenge, with larger monoliths dragged twenty miles to be uprighted, and smaller bluestones taken from quarries in South Wales before roads were constructed in Britain.

Bear in mind that when discussing Roman legions, they were expected to march with campaign gear and at the end of twenty or so miles a camp enclosure with a ditch and rampart was always dug (though loose stones were also used to build low walls in the middle east - re: Titus' campaign in Judaea in 72ad.

It is also worth pointing out that the Roman legions were being used as spare labour when not on campaign. Not because they were all expert engineers - they weren't, though they had capable men among them - but because a major project would otherwise require expensive recruitment of contractors and local labour. Always keep a military unit busy. Always.

Edited February 16, 2019 by caldrail

[Trethiwr]

It certainly is incredible the amount they achieved. 
I haven't investigated yet, the building of a wall around Alesia, (it doesn't happen for several books in the series) but I imagine that too will have involved a staggering amount of material moved in a ridiculously short time. 

It's quite eye watering when you work out the numbers. Puts it into more perspective than just saying "they built a big wall" 

 

[caldrail]

Part of this sort of thing is that it was expected. These days people are prone to acting in a very lazy and inconsiderate manner. Communal spirit was stronger back then purely because they needed support from each other and lived close enough to know who was who and what they did. Obviously human beings exhibited some of same poor behaviour - and indeed, Rome tolerated far more violence in their society than we would today.

Another case in point. A city on the eastern Nile delta was a major strongpoint in Egypt's frontier security. Pi-Ramesse was a large and prosperous community. However, the delta often changes course and when that happened the city was left without a water supply. The Egyptians responded by moving the city stone by stone to Tanis, elsewhere on the delta. Think about that. Huge monuments and structures taken apart, moved across potentially difficult terrain, and rebuilt at a new site, all by manual labour in the face of need.

But the 'Wall'. This would have been an ongoing project. We know much of the original stretch was made of turf because that was the material to hand when the Romans began construction. Parts of the wall have different thicknesses. as project management gradually ensured the wall would be built to a plan. What we don't know is how smooth the project went, other than it was completed with no apparent fuss worthy of a mention in the sources - although it is worth pointing out that there was a rebellion in Britain during Hadrian's reign. Evidence from the letters of Vindolanda suggests the Romans might have coped with some considerable issues with material supply (labour was taken care of as the military were engaged to do that). Later the wall would be whitewashed from one end to the other.