Here is the full list of all 19 War in a Box: Paper Tanks achievements.
Destroy 300 units using HEAVY-GUN
Finish the level with 1 life
Lose 3 rounds in a row
Built 25 HEAVY-GUNS
Finish the game in Expert mode
Collect 65 stars
Built 20 TESLAS
Destroy 1000 units using FLACK
Destroy 300 units using ARTILLERY
Collect 50 stars
Built 100 CANNONS
Destroy 50 units using TESLA
Built 25 ARTILLERY
Kill heavy tank or zeppelin with HEAVY-GUN
Destroy 1000 units using CANNON
Collect 35 stars
Win 10 rounds in a row
Built 25 FLACKS
Granted for first kill