Elaborating on that, when you are attacking someone's base (not a piece of territory; the actual base) the information you get from the "Army Controls" vs the info in the messages is slightly confusing. What it looks like is that in the army controls, the "level" it shows is the total amount of steps you have taken already to upgrade your base, while the messages say I "destroyed 0 levels" because I didn't reduce the real level of the base (while I actually reduced some of the steps).
This took me a while to figure out (and may not be correct)...