Here is the full list of all 11 Manor Lords achievements.
Finish the "Restoring the peace" scenario
Defeat the baron in the "Restoring the peace" scenario.
Destroy a squad of brigands with a squad of militia in a non battle game mode.
Reach 100% approval in a "large town".
Employ 24 retainers.
Get to a "small town" settlement level without hunting or gathering berries.
Face the winter and have your settlers not abandon you.
Change the church bell sound.
Big success!
Beat "Restoring the peace" with Mercenary units only.
Beat "Restoring the peace" on "Challenging" difficulty preset.