My own ACW rules distinguish between bold and cautious colonels, all of them rated 0 (best) to 4 (worst). This has little effect as long as no troops (enemy or friendly) approach their regiment or as long as they are in command control (another PIP based subsystem).
Should troops approach to a given distance and the regiment not be in command control then the regiment may react, regardless of the player’s wishes. I can’t remember the details but it’s sthg like 3+ on a D6 with one of two modifiers. Should they react then the player is constrained to have them do sthg according to a roll on a table. This is sthg like this for bold commanders
6 – charge, 5 – advance 1 move, 4 – advance half move and fire, 3 – stand and fire, 2 – retire half a move facing the enemy and 1 – retreat one move
For cautious commanders the numbers run the other way (so 6 is retreat, 5 retire etc)
Roll 1D6 and add the colonel’s rating (0 to +4). The result is the minimum action the regiment must take. A roll of 3 for example with a level 2 bold colonel compels the unit to at least advance a move with the option to charge – the unit may not do less than advance. A cautious colonel would at least retire but the player could choose to retreat.
This occurs regardless of whether the troops causing the reaction are friendly or not.
The system requires command and control to be limited (say half to two thirds of the units being controlled at any one time) and can reproduce such events as
units not reacting at all to any enemy advance; units running away from good positions upon sighting the enemy a way away; units abandoning good positions when sighting friendly units close by (their CiC, presumably, having failed to advise the relevant colonel of the proximity of friendlies i.e. he should have had them in command control) and, finally, charging or shooting at friends.
At the time of writing the rules all these possibilities seemed to be a feature worth representing in the ACW.