Bret Devereaux

I think your calculation for the length of columns could use some revision; Clausewitz says a division of 8k was an hour long, so your hypothetical brigade of 3k should be probably be considerably shorter than 1.5 miles

Depends on theater considerations, spacing, road size, etc. I was working, as I recall, from ACW figures. The local population density and thus level of forage in 1860s America was much lower, requiring more wagons.

Perhaps, but that would call into question how representative those figures are. Frederick II used 25 file platoon columns for marches, and Napoleon remarked it was almost always possible to march through the area left and right of the road, and to use two files of vehicles.

That's why the estimates come with a range. I gave 8-12 miles per day for large armies in normal march, 15-20 for small detachments, with forced marches up to 35 miles per day.

Oh, I completely agree about the overall speed of marches, the only thing was that the columns seemed too long. I would wager most armies formed the broadest->shortest columns practicable, and that this was usually considerably broader than the road surface.

Yes, that's right, though to be fair, the road situation was probably about at its best case in Europe in the 19th century (compared to anything pre-modern), so Clausewitz is probably giving an upper-bound figure.

Actually, come to think of it, the Roman triple column and square column both probably shortened the overall length of the army by using open space on either side of the line of march.