Here is an example of the kind of detail you can get into when you start digging into this game. It is from a thread asking about the types of infantry.
Mostly from Captain_Orso (AGEOD Guard of Honor and AACW Beta Testor:
... okay, some of the terms and ability names have been changed around, so let's see... Bragg, Taylor, McClellan, Halleck, and Siegel were the Training Officers in AACW; King was Training Expert or something like that.
Training Officers used to TrainUp up to 2 conscript elements to regular "line" infantry or early/late war cavalry.
Training Officers now TrainUp up to 2 of any type of elements which has the TrainUp parameter in it's model; generally militia (both infantry and cavalry), volunteer militia (if the unit say Volunteers on it) and conscripts (both infantry and cavalry).
Training Expert (King was the only one) would give each element under him in his stack (which means he had to be in command of the stack) 1 XP (eXperience Point) per turn.
Further, there is a penalty if militia leaves it's state of origin.
Yes, there is a 10% penalty to cohesion and IIRC movement.
...
The Union gets a whole slew of Volunteer units ([m][m][l]). The volunteer militia units can TrainUp to line infantry. The light infantry (a kind of precursor to sharpshooters) will not TrainUp and aside from their values are basically line infantry already.
Volunteer militia TrainUp to line infantry. Volunteer militia are only those units that actually state that they are volunteers on them.
Infantry elements can TechUpgrade to somewhat better units through events, but you cannot influence this and it has nothing to do with how long the unit has be in the field. In fact you are still building the same units in '61 as in '65, so the elements you buy in '65 will still have to TechUpgrade; the rate at which they do so in '65 is however higher IIRC.
I don't think the number of XP given has changed, but don't forget, every element with <Experience Leve 2 have a 75% chance at gaining 1XP per turn. So if you are monitoring units stacked with a "Training Driller" you will likely see that they gain 2XP per turn.
Also the tool-tip tells you how many XP you need to gain the NEXT EL (Experience Level). How many you need double for each subsequent level.
...
AFAIK there is no such thing as "Volunteer Cavalry" with respect to upgrading directly to early or late war cavalry without going through the conscript stage. Sharpshooters are similar to militia in that they are also penalized for being out-of-state, but only if they are not within a division. Once inside a division there is no penalty regardless of where the division is.
Unless my brain is going completely off kilter, militia CAN capture and hold locations in regions with <50% loyalty, but they must enter the location to capture it and remain in the location to control it. If they subsequently leave such a location, but not necessarily the region, the location will revert to being un-controlled and there is a chance that partisans appear and take the location.
Early war cavalry and raiders cannot even do that. They can however enter such a location with militia and then remain inside the location to maintain it being captured. As soon as they leave, if there is no line infantry or late ware cavalry in the region, the control will be lost, the same as with militia.
And now we have only about hundred more unit types to study.
