How far could the legions travel in a day

[Caius Fabius]

First, when you are marching long distances, you don't march in step. That is common HOLLYWOOD Garbage. I was a basic Training Company Commander at Fort Benning, in the U.S. Army. We had at least one 20 mile march every 6 weeks with basic combat load of about 20-25 KG, and many other shorter marches. (After Basic Training, and in Combat we carry much heavier loads, because we add extra ammunition, food and water). I and my NCO's marched with the men, the jeep and truck that followed carried water and any casualties.

In a long distance march, it is best to use a "route step" where the people are a bit further apart, and not trying to march in step (again, we don't have proof that the Romans did that anyway). ((Yes they learned the military pace, which may just have been a distinct length of stride.))

The shorter men are in the front of a long road march, while the taller men are at the rear, which enables the people with the shorter strides to set the pace. Since most Americans ride everywhere, most basic trainees had to first be taught to walk distances, a factor the Romans might not have worried about. At a good pace of 4 KM per hour, you can walk a very long way, especially if you stop for 5 minutes every hour for water and checking your gear, feet and buddy. The long marches were usually done along the sides of a road. I wonder if the Romans actually walked on the stone roads, or left those for wheeled traffic and couriers. The sides of a road, dirt or grass are much easier on the feet than a hard surface. However in sand or wet ground it is better to walk on a hard packed surface.

A regular basic trainee could walk 40KM in a day, if we started them early and gave them plenty of water. In severe weather days, hot, cold, wet this is reduced. In the mountains, swamps or sand this is reduced, in heavy vegetation, this is reduced. On the other hand, at the end of the march, they just had to dig a foxhole or fighting position, not put up a whole Roman fort.

Removing weight was good for short, high speed movement, but over a long distance, a soldier who is accustomed to carrying 20KG doesn't lose much distance.

The hardest courses were the "combat trainers" where you had to cover 4-6 KM in under an hour, while carrying weapons, ammo, water and a light pack, vest and helmet, and engage targets along the course, through broken ground and dense vegetation. You could fail for going over time, or for not seeing the targets or for missing the targets you were supposed to shoot. The guys with the heavy weapons had the worst of it, so we usually helped by trading weapons and sharing the heaviest loads, just like we did on the long marches.