I also heard manpower but can't say for sure. I'd like to add a follow-up question, if it is manpower - is the army size estimate adjusted for unit health? (So if I have a 1000-manpower unit at 50% health, does it calculate as 500 manpower in my army calculation?)
Nevermind. I remembered seeing manpower too, but it appears freezy responded with an answer here:
How Does Call of War Calculate Military Strength?
It's damage output
