How effective were trenches really?

[minipol]

I vented about this in the past, and still, feel so to do again
I'm trying to get a grasp on how realistic the numbers are for entrenched troops.
I really feel, the numbers don't favour the defender that much.
Look at the screenshot:



McCook marches with 4 divisions to meet B. F. Cheatam. Entrenchement percentage is 771%.
I imagine the Union troops to march towards the trenches.
I have 64 guns. If they all get 10 shots in (which is not that much), and every shot kills or wounds 5 to 10 men,
that would result in 3200 to 6400 wounded and killed soldiers.
His 27.860 troops are massed up, so the numbers are not really that high.
Also, when my troops get to fire (not the artillery), the numbers should even be higher.

On top of that, he manages to kill 2706 soldiers. In trenches of level 7?!
What use are those trenches then.
I really really really bugs me. How a slow marching opponent manages a kill ratio of 2 to 1 in heavy trenches, with
a lot of generals with attack skills of 1. To me that's an insane unrealistic result.

In the war, what were the kill ratio's for troops attacking heavily defended trenches?
Surely more than 2 to 1?
In this battle, if he managed to kill 2706 soldiers, I would at least expect 7000+ casualties from the attacker.

[Gray Fox]

I only have a crude understanding of the documentation from AACW.

Troops only actually get entrenched to level 4. This should negate about a third of any hits. The entrenchment figure above that only exists to show an additional bonus to your artillery firepower.

I believe your 64 guns are arranged in 8 batteries. They seem to be mostly 6-lbers and would fire twice at max range and then once at each additional round of firing. So about 6 shots each for 48 shots. Only about a third to one half actually hit, although each has the icon for "murderous fire". The Union has about 12 batteries doing the same firing routine with no icon.

Cheatham has a defensive stat of 5 and the other Generals 2, 2 and 1. McCook seems to have an offensive stat of 4 and his Generals 4 and three 1's. I don't know if any have special abilities that might have influenced the combat.

You took less than 13% casualties and McCook over 22% with the All out Attack set. The AoT probably inflicted the extra casualties to your side. The 7000 Union casualties you expected would only have been an extra 2%.

More important factors are cohesion which is affected by NM. Here's a link:
http://www.ageod.net/agewiki/Combat_Explained#Hitchances_in_the_Fire_Phase

[minipol]

Thanks I'll check out the link.
So basically I need heavier artillery
My national morale is at 150 vs 82 for the Union. Cohesion from my troops was excellent, they were stationed for several turns at the depot
whilst the Union troops needed to march there as all the raillines are gone. That's why I expected more casualties.