Here is the full list of all 54 Forts achievements.
The base game contains 21 achievements, and there are 2 DLC packs containing 33 achievements.
Tutorials complete
Reach the end of the campaign
Complete all campaign missions
Complete all mission achievements
Play 10 multiplayer games
Complete campaign on Hard
Complete all campaign missions on Hard
Complete part 1 of the campaign
Complete part 1 of the campaign (Hard)
Complete part 2 of the campaign
Complete part 2 of the campaign (Hard)
Complete part 3 of the campaign
Complete part 3 of the campaign (Hard)
All part 1 theatre medals acquired
All part 1 theatre medals acquired (Hard)
All part 2 theatre medals acquired
All part 2 theatre medals acquired (Hard)
All part 3 theatre medals acquired
All part 3 theatre medals acquired (Hard)
Play 10 ranked multiplayer battles