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In the history of Rome there are numerous instances of legions being marched up and down Europe, from Spain to Rome and from Rome to Syria. I'm interested to know how quickly these armies could move? Did it take a half a year to move from the Alps to Rome or did it take a week?

Also how does that speed compare to the pace of the mobile cavalry reserve used to such great effect by the late Roman emperors?

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    The practical maximum march rate is what the Germans call the "10 kilo(meter) tempo (6mph). – Tom Au Apr 3 '13 at 14:22
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    This is not a direct answer to your question, but take a look at the ORBIS project, which calculates travel times and costs in the ancient Roman world: orbis.stanford.edu – Robert Petermeier Apr 3 '13 at 16:32
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This (fun) site assumes 10 miles per day, while adding the necessary disclaimer "it depends".

However, I was not able to confirm this number in the cited source: John Pebbie's The Roman War Machine seems to refer to "10 miles" only in specific relation to a march undertaken by Caesar's army on its final approach to the Battle of Sabis.

The same book contains several concrete numbers (including references to primary sources) for speeds perhaps achievable by the Roman postal service and by individuals traveling on important missions. Here is an example:

Plutarch relates that Julius Caesar on one occasion travelled 100 miles a day for eight days in succession, driving in a hired raeda.

It relates that cavalry ("widely deployed in a protective screen around the army on the march, and penetrating deeper into the surrounding countryside") could have covered 40 miles a day. It also quotes Vegetius (5th century CE) on the practice of training marches with complete armor over distances of ten miles from a camp plus return:

Decem milia passuum armati instructique omnibus telis pedites militari gradu ire ac redire iubebantur in castra ...

And FYI, here is a later account (again from Andrew Wheatcroft's The Enemy at the Gate: Habsburgs, Ottomans, and the Battle for Europe) that quantifies daily distances traveled by an Ottoman army in the 17th century:

The whole force could advance only at the pace of ox carts and the cannon, perhaps twelve miles a day.

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From the Summary in Observations on marching Roman Legionaries ..

the Roman legionary probably carried no more than 40 kg of clothing, equipment, food, arms and armour;

a legionary in a typical campaigning day, marching on-road 29 km in approximately 7:30 h and building a temporary marching camp, probably expended between 5500 to 6000 kilocalories of energy, and required the same in replenishment;

the legionary would require between 9 and 11 litres of water to avoid dehydration and heat stress;

off-road marching required the expenditure of less energy than when using a road;

a typical legionary (body weight 80 kg, load weight 40 kg, march velocity 1.2741 m/s), could have marched along any of the roads in Britain for an energy expenditure of between of 501 to 542 watts;

Roman legionaries had an on-road march velocity in the range 1.2741 to 1.3411 m/s (2.85 to 3.0mph or 4.59kph to 4.83kph), with the lower value being more likely to have been the more common velocity;

at an on-road velocity of 1.274 m/s for 29 km, the last ranks of armies greater than 3 legions in size would have arrived after sunset, therefore, large Roman armies marched in multiple columns (August 11th daylight hours);

Roman legionaries were expected to march for 7 to 9:30 h each day – these times were not exceptional, did not overly tire the soldiers, and would have been sustainable, that is, the norm for either on- or off-road marching;

off-road velocities were probably in the range 0.6706 m/s (1.5 mph, 2.41 kph) to 0.7639 m/s (1.71 mph, 2.75 kph);

off-road, single column marching over 15 km or more, and for legion strengths greater than 2, was not a normal, sustainable option and requires other marching strategies;

all armies over 2 legions in size probably marched off-road in multiple columns to reach their destinations;

a) Roman armies of 1 and 2 legions in size could have marched in single column along a road; b) armies greater than 2, possibly 3, legions marched in multiple columns, whether on- or off-road.

  • Considering my own experience backpacking with about 25 kilos in luggage the 9-11 liters of water seem ludicrous, only necessary in a desert maybe. The calorie intake seems a bit high as well, I´ve never had to eat twice as much. – Jeroen K Nov 5 '17 at 19:48
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I know this is an old question but I think there is a really good tool that is not mentioned here. There is a comprehensive model that was created by Stanford to model how long travel took in Roman times, since you are interested in Military be sure to set your options correctly, under Mode Foot be sure to select Rapid Military March (or Ox-Cart or whatever depending on the armies method of travel,) also Select River and change to Military. This model allows for so many variables including type of march, season of march, method of transport. It will give you a very good approximation of the travel time from different cities in the Empire.

http://orbis.stanford.edu/

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Scipio Africanus legions marched on an average of 26 miles / day to get from Tarraco to Carthago Nova in 6 days, but those are extreme numbers on a very forced speed, usually, it would be half that amount.

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John Harrel in "The Nisibis War" uses an estimate of 10 miles per day -- roughly 16km a day -- for "normal" conditions. They could go faster, at the cost of exhaustion or a less well-developed camp, or they could go slower, if conditions like heat or terrain forced them.

One of the interesting facts is that a large enough force would have the vanguard and scouts setting up the next camp before the rear guard left the previous camp!

  • In what sense is 15 miles roughly 10 km? – kimchi lover Jan 14 '18 at 15:22
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    You have the conversion upside down: 16 km is very close to 10 miles. 15 miles would be ~ 24 km. – Pieter Geerkens Jan 14 '18 at 18:58
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The question is how quickly could Roman legions move? Well a single soldier in the modern U.S army is required to complete a Loaded March, carrying weight of up to 70 pounds, of 12 miles in less than 3 hours to attain an Expert Infantryman Badge. The 'Raid March' practised by the French Foreign Legion requires a march of 75 miles in 3 days in full combat gear carrying rifle and 70 pounds of gear. A Full Pace march for a Roman Legionary in basic training required a march in daylight hours of 22 miles. Clearly it is entirely possible a Roman Legion could march 20-30 miles per day if needed. It is well documented Roman soldiers never stopped training during their 25 year service and it may well be a mistake to underestimate the fitness and endurance of a Roman soldier compared to that of a modern soldier especially given the only mode of troop movement available to a Roman foot soldier was the march.

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    Sources to support your assertions would greatly improve this answer. – sempaiscuba Jan 14 '18 at 12:00
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    There's a huge difference between marching for a day, marching for a week, and marching for a month. 25+ miles in a single day is easily attainable, since you don't need to carry more than your weapons and armor. A Roman army could probably march at high speed for two weeks, since (post-Marian-reforms) they carried most of their equipment and two weeks of food themselves. Beyond two weeks, the speed at which a legionnaire could march is irrelevant, since the army's speed is constrained by the speed of the baggage train. – Mark Jan 16 '18 at 2:13

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