There's your soldiers, going out on mission after mission with a song in their heart and barely any break in moral except when mindcontrolled.
Do you desire something...darker? Grimmer? Grimdarker?
If you want to start a new campaign like playing Darkest Dungeon and XCOM together, you might want to try Grimy's Morale Mod.
Although I don't know if Long War 2 can be won with Grimy's Morale Mod. I just did LW2's Gatecrasher with it and though escaping with no wounds, 4 of 8 soldier's got shot at enough that their will is almost gone. If they'd had any more stress, they would have panicked and hunkered down and been useless. And now back on the Avenger, they'll get all their Will back when they get promoted. But I don't know if you can maintain the soldiers' Will during the length of a campaign, even with slow recovery of Will and the R&R slots in the Bar to help with that.
If interested, you have to start a new campaign. Installing Grimy's Morale Mod on an existing savegame will get you the Will damage in combat and soldiers breaking down and panicking (and in LW2 they just hunker down). But you don't get the vital Bar R&R slots to help them recover their will.
I haven't played LW1, but it's kind of like putting LW1 and LW2 together. A larger team will be needed as soldiers must spend time out of combat. Trying to forget the horror.
Even though I'd have to do yet another campaign restart (by following on from this savegame), I'm tempted to do so. But I wonder if the troops moral will hold out, especially in long drawnout missions with lots of fighting? Hey, most of my other gameplay mods make resources more plentiful and things slightly easier. I think I will give Grimdark Long War 2 a try. Because Will damage happens to ADVENT too.
Because I want to be able to crush the will of the ADVENT troops, see them driven before me, and hear the lamentations of their Elders!
(Since Grimy's Moral Mod predates LW2, it takes no account of things like soldiers either as Haven Advisors or on Infiltration and thus not being on the Avenger. I will have to play nice and not accidentally let them spend time in R&R.)