Here is the full list of all 37 Third Front achievements.
Diversion prevented
3 cities are captured
Earned 50,000
10 cities are captured
20 cities are captured
50 cities are captured
100 cities are captured
150 cities are captured
200 cities are captured
250 cities are captured
Captured all the cities
The population reached a mark of 5,000,000
The population reached a mark of 20,000,000
The population reached a mark of 50,000,000
The population reached a mark of 100,000,000
Earned 500,000
Earned 2,500,000
Earned 10,000,000
5 diversions prevented
10 diversions prevented
25 diversions prevented
Found 5 diversionists
Found 25 diversionists
Found 125 diversionists
Found 500 diversionists
5 units of equipment were purchased
25 units of equipment were purchased
125 units of equipment were purchased
500 units of equipment were purchased
The main building is improved to level 5
The main building is improved to level 10
The main building is improved to level 20
The main building is improved to level 30
The main building is improved to level 40
Complete the USSR campaign
Complete Germany campaign
Complete the Alliance campaign