Only a few -

Financial calculations could be made clearer. At first, I was confused for which turn I was doing my calculations. However, this is only wording, not something wrong with the financial system.

Control of Units in battle being led by another player - as is shown, You kind of abused my men and I gained nothing for it. Had I been in the battle, I would have ignored your men and fought it out myself, with only just my men, and would have suffered fewer casualties. We need to be able to select whether or not we wish to have our men participate in battle. Otherwise we can have some disgruntled players being abused by someone with more command.

To solve the above, make it that separate players must maintain separate stacks, so that they cannot merge. If a battle occurs, the player not playing also needs more say - does he wish to act as reserve (as I would have wanted), or does he wish to take to the front? A combination? This will keep players happy I think.

Finally, I'd love to be able to have multiple avatars to control. This may be unreasonable however, so we could limit ourselves - maybe to an Adjutant?