Here is the full list of all 20 Valiant Hearts: The Great War achievements worth 400 gamerscore.
Finish the game
Save Karl
Save Karl for the third time without making any mistakes
Find every single historical item
Shoot the German flag with the cannon at Vimy's ridge
Escape the French army with Anna and Karl
Defeat the Baron Von Dorf
Save your entire platoon during the battle of Somme
Push all the laundry bags
Finish the Douaumont Fort mission
Rescue Karl from underneath the zeppelin
Find 50 historical items
Ring the bell 3 times in Ypres
Read 30 historical facts
Witness the zeppelin crash
Complete 1 taxi mission without damaging the car
Shoot the tractor before it crushes Emile
Pet the dog
Find 5 historical items
Raise the flag at the end of the basic training