So I just "lost" the 2nd Battle of Bull Run as Union, because I lost more than 40% of my men. I achieved my official objective and the game doesn't even grant me a draw (not to mention that my Rearguard was completely absent from the fight for reasons never explained). At other times I'm about to reap the benefits of my efforts just when the timer is down. Like his main Northern lines starting to collapse rapidly and I'm about to drive every last one Rebell off and capture their artillery. Or when I have the enemy outnumbered and encircled at North Malvern Hill, with East and West captured, and get only a draw as Confederate. All this is pretty frustrating in its own right, but it also significantly affects your future campaigns, so the frustration carries on.
There are some easy and a few difficult changes to the game which would make it so much more enjoyable:
Actually tell us what all our objectives are. This should be easy, right?
Actually tell us what happens when the timer runs down.
Break down objectives into smaller ones. Example: 2nd Bull run, -5 reputation if casualties > 25%, -7 if >35%, -10 if >45% and so on.
Hand out reputation only as a result of a battle and grant fixed amounts of manpower and $ after each Grand Battle. This would make Politics actually useful, generate more interesting choices (do I hold back in this minor battle and face the consequences because my manpower is low?) and make things a little more calcuable.
Make the timer more dynamic. Battles shouldn't end at exactly 5:51 pm or something, especially when the battle just reached its climax. And also make it a player choice whenever possible.Using the day/night circle is a good start. Units could lose max endurance and efficiency during the day, even more so when they're engaged or running around. This limits offensive capabilities in the evening and makes planning for reserves more valuable. Instead of setting a dead limit of possible operations, give us choices and make them explicit. Like: When and how many units will I send to the main battle, when I already have difficulties pinning down this Jackson fellow? Do I order a major offensive an hour before nightfall, knowing things will get really messy if I'm not done in time? What troops am I willing to sacrifice to cover my retreat (instead of hold this hill for X hours, no matter how hopeless the situation gets in the last 30 minutes)?
Give the game a way to roughly assess tactical situations, like encirclements, possibly through more minor tactical locations and a weighting of troops in locations ("holding" a hill with 100 skirmishers isn't much of a holding, having 1k infantry up there is a different thing). This could also trigger the AI to try and break through or retreat and would allow for a more nuanced victory point distribution. Make and allow for actual retreats and avoid ridiculous situations in which the battle stops when its currently reaching its climax.
You may or may not agree with any item on this list, but I think my main point is definetely legitimate: Give the player meaningful choices and enough disclosure to actually make them, instead of setting rigid, opaque, mechanical limits.