Here is the full list of all 23 Foreign Legion: Buckets of Blood achievements.
Kill 2500 chickens
Kill 1337 enemies in total
Kill 5 enemies with an air raid
Reach level 20
Kill 4 enemies with one rocket
Beat the Village in the extreme difficulty
Survive 30 minutes in endless mode
Find the minigun
Purchase the Foreign Legion FAMAS
Kill all enemy waves in 7 minutes
Play a game with only the Night Vision Goggles equipped
Finish the campaign on any difficulty
Make a kill chain of 10 kills
Repair the town hall 5 times in one round
Make 15 headshots in one round
Destroy the supreme chicken overlord
Play a game with only the Peace Badge and Bullets equipped
Escort the bus safely without it taking damage
Play a game with only the Smiley Badge equipped
Win the game with all civilians alive
Kill all chickens in one round
Kill 25 chickens
Purchase an outfit, helmet and accessory