[ErikCumps]

The bare minimum is one save file from each battle, taken at a consistent time, either
always at the start of the battle (deploy, or turn #1) or always at the end of the battle.

This will provide you with basic campaign tracking, but it will miss info about the core
force changes during the last battle (if you only use saves from the start of each battle)
or during the first battle (if you only use saves from the end of each battle).

So I suggest to always add at least two saves from each battle: one at the start and
one at the end. This will give you adequate campaign tracking, including info about
what happened during each battle.

If you also want to track what happens during the battles, you will have to add additional
saves to get more detail. The more saves you add, the more detail you get.

Of course, adding a save for each turn gives the most detail. You can see the evolution
for each unit and formation as the battle went, and, if you look at the Strategic Map, you
can see the positions change with each turn.

Erik