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