we used War and Peace to genarate battles for Napoleon's Battles.
A long time ago now (late 80's/early 90's)
If I can lay hands on the mechanics then I will post them.
From memory we used a look up table. As each counter in W&P represents 5000 troops this equated to 10 bases in NB.
So 1 W&P point gave a brigade of 5 infantry, a brigade of 4 infantry and an artillery base. 2 W&P points gave you double. 3 W&P points gave 3x5 base infantry, 2 x 4 base infantry, 1 x 4 base cavalry 2 foot and 1 horse artillery.
Mounted points gave 2 x cavalry brigades. Guards, Cossacks, Landwehr, etc were used if you had those W&P counters.
We used it for an Austrian vs French campaign and one against the Russians and Austrians.
Thanks for the quick and helpful response. Would very much appreciate the mechanics you used if you find them. I can let you have my email via personal message if and when you do.
Players on both sides had to agree that it was big enough and balanced enough to move to the tabletop otherwise small or lop-sided battles were resolved using the W&P combat resolution table.
It was a lot of fun at the time.
Other boardgames to consider are Napoleon (1815), and Napoleon at Bay (1814)