The history of the campaign is pretty straightforward. I am assuming you are unfamiliar with it. Otherwise I would find your comment about the play balance kind of interesting and revealing ...
Suffice it to say that anyone playing the underdog (which the Allies are in this scenario) SHOULD scout it out so that CAN determine how to win glory and honor for our Allied forces over the dreaded French serpentine legions.
Yes, the French have the numbers. However, the Allies have the numbers in artillery and their cavalry is dynamite. If you are half the player in this series as you are in the ACW series (having beaten my tail every time we played) you should be able to come up with a good combination of troop types that will at least give you tactical superiority in several situations.
There are several chokepoints where you can set up a killer defense with the Prussians. If you double stack their battalions the French will have a real time trying to dislodge your stacks (given that you use terrain to protect them from artillery fire).
There are several what-if situations you can play on the big map. In one of them I add in extra Prussians and also the Russians. That makes for a much more "balanced" battle. However, it all depends on the players too. I have seen the numerical advantage of the French player frittered away due to incompetence or impatience. Also the decisions that the French makes early on as it regards march routes is important.
If you want my two cents on strategy let me know and we can adjourn to the Allied forum and I will provide a map showing the likely routes and how to defend them. 20 turns is not a lot of time in this one. You can still adjust your troops to meet the French force. Just know that in this one you HAVE to play for the long haul and a quick decision will not be forthcoming for either side. In other words, get Louis and the Advance Guard outta there!

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Generalfeldmarschall Wilhelm Prinz Peters von Dennewitz
3. Husaren-Regiment, Reserve-Kavallerie, Preußischen Armee-Korps
Honarary CO of Garde-Ulanen Regiment, Garde-Grenadier Kavallerie
NWC Founding Member
For Club Games: I prefer the Single Phase mode of play. I prefer to play with the following options
OFF:
MDF, VP4LC, NRO, MTD, CMR, PR, MIM, NDM, OMR (ver 4.07)