A common tactic for Cavalry at the time of Custer, was deploying 1 Battalion to lay down fire while a reserve Battalion formed up and got ready behind. When things started getting hairy, the 1st Battallion would bug out by leap frogging behind the reserve. This would give them time to reform and take over next. In this way, a very small Cavalry force could fight in a sustained conflict with a much larger force. (assuming they don’t run out of ammo)
Most games don’t simulate this dynamic very well. How does the Pub Battles system model this?
The Cav are small in numbers but they can be very subborn. The Sioux are treated as militia. The Cav are regulars. The result of this in the battle is that the Cav stands and holds relatively easy. The most common result is the Cav stands and the Sioux flips and retreats or is killed. About every 3rd shot flips a Cav.
So, after a couple waves of assaults, most of the Cav battallion ends up flipped. Now they ARE at risk. About every 3rd attack will destroy a Cav Company!
Now, if you had a reserve Bn to the rear, no problem. You hold until the front line becomes mostly spent. Then retreat back behind the reserve Bn. They can rally while the reserve holds the line for a few turns. Then they can switch. This models the common ‘leap frogging’ tactics for Cavalry at the time very well.
The problem at Little Bighorn is: There usually aren’t any reserves. Or the reserves are getting pummeled from another direction. This situation is made even worse by your line getting overwhelmed and flanked on each side. This allows for multiple shots on the Cav which is very likely to flip them in the first wave attack.
Then you end up with an agonizing decision to make. Your line is flipped. What do you do next turn? You can retreat OR rally. You can’t do both. Do you stand and rally so you can fight another turn or two? If you do, you will most likely get enveloped. With some luck, you may be able to fight your way out and fall back. The other option is to retreat but then you stay flipped. Your units remain vulnerable to getting killed in the next combat.