In the middle of the 2000s (something like 2004-2006) I was watching an animated TV series, whose characters were mice.
There was a city with a citadel, and guards (also mice) were guarding it.
I remember that this series was quite long, and I was watching it for several months.
The appearance of characters reminds me of Mouse Guard:
But in this series, the mice had smaller heads (more anthropomorphic).
