I cannot figure out how, with almost 3-1 advantage Lee against Rosencrans I can lose so badly. There is nothing in the battle report that explains those results. This doesn't make any sense.
This was my reply. I hope you'll chime in with your observations and questions as well:
I have seen such results many times. I restored the previous turn in your game and re-ran it 4 times, to see what would happen. (These results are displayed below the maps and battle reports.)
Battle Conditions.
The common denominator to all battles was that they were fought in the hills against entrenched troops - not the ideal conditions for offense. NM was slightly in the CSA's favor, 100 to 79 (as I recall there's a slight penalty below 80 - I'd have to look it up though. You get no bonus for 100.). Hooker was entrenched with two divisions (lvl 3 but only 4 days away from lvl 4) and set to "hold at all costs." His troops were pretty average, with no experience and only one elite unit, the Regular Bde. He had lots of arty, and French to lead it, but this was somewhat offset by being in the hills. Hooker had the only union supply unit in the region: 0 GS, but 80 ammo. Interestingly, Hooker does not appear on the CSA map! Pope is also shown with lots of troops, almost all of which were actually detached, extremely weak, and scheduled to be out of the region by Day 8. Rosecrans, also not on your map, was moving in from the south on G/G with a relatively weak division and no SU. Pope had no troops. Given that you had Forrest with NINE cavalry brigades in the adjacent area, the lack of knowledge about what was in Humphreys is somewhat surprising! There were lots of union ironclads nearby, but none were set to bombard. Whipple's weak corps was adjacent in Ft Donelson, but did not MtSG. Buell's corps was across the Cumberland and therefore could not MtSG. You had 60,000 (at least on day 15), and the Union had 28,000. This is more like 2-1 than 3-1, although you will note on the battle reports the effective force was more like 3-1.
Map of the Area Before the Battle from the CSA View

Map of the Area Before the Battle from the USA View

The Battle Results
Day 14 Battle

Day 15 Battle

As I said, I restored the previous turn and re-ran the battle four times. Here are the replay results.
1. You lost men (but not units) at levels comparable to the tourney turn, but only one battle and -4 NM.
2. You won, but with more losses than the Union and therefore got 0 NM.
3. You lost one battle, -4 NM, but Sid Johnston stayed in the region which was still 100% Union MC.
4. About the same result as in the tourney turn, but only one battle -6 NM. Sid J stayed in the region, along with Hooker (who still doesn't show up on the CSA map!!!) and Rosecrans.
For the tourney turn, the sequence of movement caused your army to fight on day 14, and then receive a reinforcement on day 15 which caused a second battle. This did not occur in any of the replays, where all battles were on the 15th day.
The random number generator was not your friend. First, Sid Johnston arrived on day 14 and started the fight "early." When the rest of your army arrived on day 15 you fought again. In the four replays, he did not start the battle on day 14 and your army fought only on day 15. Having two battles instead of one was not in your favor in this instance.
Second, you took heavier losses in both the tourney battles than in all but one (#4) of the replays. Mostly this was because there were two battles. In replay #1 and #2 the losses were about the same as in the tourney turn, but only for one battle - but the Union had units eliminated too and you didn't lose so many, which lowered the NM loss from 6 to 4. And of course in one replay you won - although you still took more losses than your opponent so you got no NM.
I thought your expectations for the attack were reasonable, but your forces were not prepared in advance - they were scattered all over, had to move to Nashville and then coordinate an attack that could not possibly start until Day 14 the day your first unit, Sid J's corps, was slated to arrive. I find it remarkable that ALL your units managed to join in on the attack in EVERY turn, both the tourney one and the replays. Also, your knowledge of what was in the region was very different from what turned out to be there, although I expect you might have gone in anyway had you known, with Lee available to lead a 2-1 charge.
In subsequent email discussions, I got these replies:
from Moni Kerr:
Thanks for looking into it. I suppose the movement of Jackson and Johnston and the battle taking place on day 14 had a big impact on how many troops actually took part. Jackson was congratulated and Polk's corp took some damage so they obviously participated at some point. Johnston was set to conservative attack so I don't understand the very high losses with no attempts to retreat.
I had 3729 pwr vs 1490 pwr which is almost 3-1 and my combat report shows 122 sub units deployed at the start vs 71. The weather was fair that turn, it only changed to mud for the current turn so there is no combat penalty for the attacker. (Shanks speaking: I had previously noted incorrectly that the battle was fought in the mud ... although it's never clear to me exactly WHEN the weather changes).
The note about not not seeing what is in the region is interesting. I've been hampered by this all game and have wondered why, especially here with so much cav available to me.
from Rattler:
I agree with MK on how that battle is unhistorical with a OOB he had. It is just another example on how OP trenches are so early in the game, which is why I am so aggresive in the first year. While I agree that the battle results are very uninformative, by looking at the range losses I would attribute the victory to the USA's quality of guns. The battle report also doesn't give any MTSG units into the count, I currently have nearly 40k men and 180 guns in the area after the losses in the battle. I know they took part because the small division of mine that was destroyed was not even at Humphrey's, but the garrison at Donelson.
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As I said, additional comments welcome.