In a nutshell, the Union got clobbered. Here's what happened:







The next result was that Grant's corps was practically annialated. That last battle saw both his corps supply wagons getting captured. As you can see, nothing is left in those 3 divisions except for artillery elements:

In comparison, Thomas' corps is comparitively unscathed. It still has lots of ammo in fact, whereas Grant's demolished corps has none (not surprisingly).
As a result of so much element loss in those last 4 days, the Union lost 11(!) National Morale. The CSA seems to have gained a similar amount. To add to my misery...Grant, Sherman and Kearny all got blamed for the disaster. Grant had enough senority to take command of a new 4th army prior to the disaster...no more. He got bumped down to 6th in senority. Sherman lost 5 levels of senority, meaning it will take him years now at this rate to get his second star.
So, my question is: What just happened?
It seems to me what happened is, that despite the event message I got prior to the first battle announcing that Thomas' corps was joining in the battle, AND despite seeing his forces and leaders in all the 7 battle reports above...he really did not contribute to the majority of those battles...particularly the latter ones.
It looks to me like Thomas corps mostly sat and did nothing, as Grant and company launched several attacks at bad odds, and attacked themselves into oblivion.
Now I know that sometimes seperate forces can be involved in combat seperately in this game, and it is somewhat random what stacks participate in a round, and which do not...but what happened in this case seems a bit extreme.
I have to ask myself...if Thomas was sitting some of these rounds out...why did Grant attack? Shouldn't game algorithm called for Grant to retreat in this circumstance, calling off the suicide attacks?
Seems to me the CSA, in comparison, benefitted greatly by keeping his forces in a large unwieldy -25% stack. Not only did all his forces participate, in every round...but more importantly, he was able to spread his losses out, avoiding the morale and seniority killing penalties Grant, Sherman and company suffered from, due to element elimination.
If this is somehow not a bug...I think how the combat system treats battles with multiple cooperating stacks like this might need to be tweaked a bit.