Wraith wrote:Would then, late game, the ideal be a "cavalry corps" in the Army Command for a MTSG benefit? In that they're wicked fast to get into the field?
No. 100% cav divisions perform suboptimally in Corps and Army scale battles. (You will have to take my word that this is something I have sandboxed and tested extensively, so this claim is both empirically grounded as well as wiki-based). Cav participating in large battles really do best when mixed into majority or at least partial infantry divisions.
A cav-Corps' speed would allow it to MTSG slightly more often, but even stacks with slow moving units have a high chance of MTSGing if the travel time is less than 10 days. An all-cav Corps WOULD be highly likely to MTSG but would perform poorly once it got there. If you take care with how you position your Corps and Armies you can give yourself a pretty high chance to MTSG with heavy forces as-is, so it's not worth it to trade increased MTSG chance at the cost of poor performance on arrival.
Because of the way cav elements are treated by the engine, they do not take hits until all the infantry elements in their unit (divisions are units) have received at least one hit. Cavalry replacements are more expensive than line infantry replacements, and you have fewer of them in your replacement pool. A 100% cav division will begin costing you expensive-to-buy cav replacements from the very first hit it receives, while a mixed unit (divisions are units) has a meat shield of cheaper and more available infantry to soak up the initial batch of hits. Assuming you have a cav officer in the Corps/Army stack then cav, especially late-cav, are equal or better than conscript infantry, and slightly weaker than regular line infantry, so a division with 2-4 cav mixed in does not suffer a detrimental loss in combat effectiveness. Additionally, all-cav divisions fare poorly in the assault phase compared to line-infantry or mixed divisions; having infantry in the unit to stand strong during assault phase (not to be confused with assault posture) makes a big difference in relative divisional performance.
The underlying MTSG mechanics also work against all-cav MTSGers, or any other underpowered MTSGing stack for that matter. When MTSGers enter the battle, the friendlies who were already present will mostly sit out for a round and the MTSGers have to do all the fighting (and MTSGers don't benefit from entrenchments, even if the battle is defensive). If the MTSGing stack is small relative to the opponent's force (which is likely if you are trying to use MTSG to cover a broad front) or has suboptimal composition, it will take a lot of hits and not do adequate damage to opposing divisions, risking failed shaken and morale rolls, which then have a cascading effect across the rest of your troops. Forget the idea of a small reserve Army force of any kind MTSGing to save the day, be it cav, artillery or what-have-you. The manual is just plain wrong when it implies that this is how you should use Armies. Any stack that MTSGs into a battle needs to be able to hold its own for at least one round against the (probably) corps sized stack it will be facing on its first round of combat. As a rule of thumb, assume that at least two full divisions will fit into the frontage of any large battle, so a MTSG stack needs to be at least that size and with an appropriate composition to not get pawned when it shows up to battle.
I have seen many battles where the total forces available should have been good enough to win but a too-small MTSGing stack cost the battle.
Later in the game I often put together "finisher" stacks consisting of 8-10 infantry, the rest cav and some rifled artillery either in the division or at the stack level as CPs permit that lurk just far enough int he back that they do not MTSG to battles they can't handle. I give them a Cav leader (JEB Stuart is perfect for this, and I organize him as a Corps so he gets bonuses but I don't make it "corps sized") and use it to lay into retreating stacks that have overcommitted and lost at their point of attack. The Cav give them extra patrol to increase the likelihood they can actually bring retreaters (who are usually in passive posture) to battle, and the infantry and artillery deal enough damage to seriously harm the enemy and force them to withdraw without incurring excessive cavalry losses. (You have to be in orange/attack posture, hence the rifled guns). These, along with scouting or other small stacks to block retreat paths can herd retreaters to progressively worse positions while continuing to deal damage until the retreaters either evaporate on their own or I can execute a stack-wipe. The number of cav gives the opportunity for a fair amount of pursuit damge (the enemy will tend to retreat since they are in passive posture).