Here is the full list of all 32 Battle Nations achievements.
Win 25 Attack Missions
First Flamethrower Ignition
First Raid Mission
First Attack vs. a Friend
Play PvP With a Friend
10 Soldiers in Your Army
Construct 15 buildings
First Attack Mission
Kill More Than 1 Unit With a Single Attack
Own 2 Barracks
First Steel Mill
First Occupation Mission
Win 25 Raid Missions
Own 25 Districts
Win 25 Occupation Missions
Defended Against 5 Consecutive Attacks
Defended Against 15 Consecutive Attacks
10 Full Garrisons
Defeat an Army of 12 in 12 moves
Defeat an Army of 12 in 8 moves
Defeat an Army of 12 in 4 moves
Bring 12 Soldiers to a Battle
Defeat an Army using only Artillery
Win 10 Battles in 10 Minutes
Play PvP With Friends 100 Times
Participate in a Boss Strike while in a Guild
Earn the Tier 1 Prize in a Boss Strike
Earn the Tier 10 Prize Boss Strike
Earn the Tier 11 prize in a Boss Strike
Contribute 100 points toward a Boss Strike!
Contribute 2000 points toward a Boss Strike!
Contributed 10,000 points toward a Boss Strike!