Pariente, I haven't had a discussion this good about tactics in many years. Thanks!
The original problem was how to deal with low visibility and assumed that we already know that our army on the field isn't facing a much larger force, but an equal or smaller one.
If I don't know my enemy's strength or the composition of his forces, I'll send enough cavalry to find out before I commit myself to battle. In a campaign situation I may decide I don't want to do battle with that enemy in that location. Or I may decide I want to tease him into attacking my smaller force while I defend and wait for reinforcements. If I send my smaller force directly against his larger one, without knowing he's larger, he has achieved the element of surprise. The only reason I'd want to attack a larger force like this is if the enemy is trying to avoid battle and I want to fix him in place while I send a larger force to destroy him.
If I know my forces are at least equal to the enemy and that the enemy intends to give battle, which is the situation in the Montebello scenario, then I have no problem with opening the battle by sending one corps forward without initial recon. I have probably already given a second corps orders to advance an hour and a half after the first, and will commit additional reserves as necessary.
It is my intent to keep the initiative and force the enemy to react to my movements. I hope to force him to commit his reserves before I have committed mine. If my two corps meet the enemy's main thrust, then they have at least spoiled his attack, disrupted his formations, and if he continues he will meet a fresh defensive line with his weakened and scattered forces. Meanwhile I've sent another corps from my reserve to flank him.
One complaint I keep hearing about the Montebello battle is that there are too many forces on a map that's too small. I find that the concentration of forces is just right. You can't make a wide sweeping flanking movement, but at some point the enemy will advance beyond one of my corps who can attack the enemy's flank as they pass, or some of my forces will advance beyond the enemy's main lines and can flank his forces from there.
This will be very interesting in multiplayer against a human opponent. I will be adjusting my tactics as necessary. But if my opponent prefers to wait for a cavalry recon before he orders an advance while my corps starts moving immediately, with or without recon, I have at least stolen an hour's march on him and given myself more room to maneuver the rest of my forces. That initial corps isn't there to do recon, he's there to fight. The fact that he's also gathering intelligence is a bonus. If I find myself surprised too often, you may assume I'll be changing my tactics.
Hook