I would offer that it's not so much operational groups, but operational areas that you need to concern yourself with.
Here's something else: The logistics of an army on the march. For all the discussion about tactics, frontages, etc, the REAL wrk was done in actually getting the troops where they needed to be in a timely and organized manner.
Both sides used almost identical methods. You had to take a look at the available road network, where your various Corps were located, the size of the trains, both Corps and Army, available water supplies along the route (and foarage for the animals). All of this was, of course, predicated upon where you wanted to get to.
Although a Corps could, in fact, cover 30-35 miles a day, you couldn't keep up that pace. You lost unit coherency due to the immense number of stragglers, animals couldn't keep up that pace pulling artillery and wagons, and any cavalry that did that speed would be useless for anything else.
The Army considered 10 miles a day to be best speed, bumping that up to 20 miles/day for short periods (3-4 days max) and anything above that for in extremis situations only.
So once you had your intelligence reports in, and sorted/sifted and outlined, then the Commanding General and his staff could consider the next day's objectives, then look at the best way to get there. Napoleon developed the model of marching across country with each corps between 1/2 and 1 day's march apart, thus able to support each other. They marched in a diamond shape, with one corps in advance, one corps and army HQ in the middle, one corps to each flank, and one bringing up the rear. In this manner, no matter which corps made contact, at least three more would be able to turn and/or maneuver into support, with the furthest becoming the reserves.
In addition, each day's march saw a different division in the lead of each corps, with the brigades and battalions also taking turns in the lead of their respective organizations. That way, units tok turns in the lead, rather than at the tail eating dust all day. It also allowed those men in the read Divisions, etc, take a little extra rest while the other units marched by.
Plus, you had to send not only scouts ahead to recon the route of march for the enemy, but also engineer officers, QM, etc, to search out suitable bivouac areas, water supplies, pasture/forage/grazing areas for artillery teams, cavalry and supply trains, etc. THOSE guys were up early and left well before the rest of the troops were up and on the march.
Lots of stuff that most gamers don't want to have to deal with, but consider that a single army corps, with it's supporting trains, ambulances, division hospitals, etc, could easily take up 20 miles of roadway if in a single column, at normal intervals. So when considering running an entire 3-day battle like Gettysburg, road networks, water supplies, parks for the various trains, etc, all play an important part in how things develop and unfold.
To my mind, it not how well they performed that amazes me, but that they were able to do it at all.
completes a Confederate river ironclad.
