I have a pet peeve... that the Battles follow some form of realism through the play and way units operate.
Here is a an example of a good thing: The Cavalry symbol (like a chess knight) in Waterloo map can attack both the unit next to it and also the one that is two spaces away provided there is no impassable object.. fine.. wonderfully done.
Now.. an example of something that don't fit. the artillery pieces enter into long distance combat where the other units are at the other ends of the map... but even lowly infantry is allowed to return fire and kill off the artillery during the exchange.
Artillery is "Indirect Fire" and is NOT susceptible to damage from return fire from troops that are not directly adjacent to it... or in the case of the Knights above two spaces...
If the Unit would not ordinarily be able to attack the artillery emplacement then they should not be allowed any return fire.
Now you may think this would make artillery too powerful... but the artillery would need to be limited only in its number of attacks per round. IE: One Volley per Artillery unit so you better make it count. or... One Volley per group of 5 cannons and then putting 5 men on one cannon emplacement would count allowing you to take one volley... 20 would allow you to make 4 volleys etc.
What think ye?