Aaaand another one. :D

Picture is attached. I invaded this system, protected by a citadel and all. 

All my troops have equal (infantry) or better hitpoints than the enemy, and I dealt more damage to the opponent. Yet looking at the presented remaining manpower, it sure looks like I lost more, if barely. 
How exactly does that translate? Did my troops just barely not deal enough damage given they have more armour?

I also have a minor faction quirk that makes my troops cost 10% less manpower. I would assume this to influence the results the other way around, if at all, but you never know. 

Any hints?

Thanks in advance.

Edit: Maybe "Enrollment rate" is applied immediately after the battle? 

Edit 2: 

And what's with the war score:

0 seems a little low.