For most opponent pairings, you will get to know which side they play from after a little experience. However that can change e.g. UK vs Gemany in the desert in WW2 to Europe. In MBT though against some partisan opponents, the side can be random (I think vs VC, and PLO are ones?).
It is not a problem in the attack as one side owns all the V-hexes but can be confusing in the meeter as all are usually neutral. In the original SSI game, one clutch was allocated to each player and one to neutral - meaning the only battle was really for the middle clutch, but since the one on your side had your flags then you knew what side you were on. But there was no way to change the map or placement other than exiting and restarting the entire process in the original game.
We are thinking of a way for players to see what side of the map they have assigned in a battle, probably in the View Map function for the next release. It could be an "extra" flag on each map side (but some players may report that as a bug as there are 2 too many flags!
) or perhaps on the Battle Report button we can report left and right side of the map alongside the battle type and the 2 players.