If there is something to add to the solution or you have any qustion please tell me in the comments.
This is a story related achievement.
in order to get it you will need to complete operation D
operation D consists of 5 missions
the missions shouldn't be hard
If you are struggling with a mission i have have added a walhthrough of all mission in operation D with gold stars for this achievement:
*Warning the video might contain spoilers
D-1 starts 0:49
D-2 starts 5:06
D-3 starts 9:42
D-4 starts 16:41
D-5 starts 20:08
*Note if you are going for gold stars watch the full video and don't forget to choose the same loadouts and XP boost if needed(in loadouts)
*Note i am not the creator of this video, credits goes to: FusionOrbs on youtube
https://www.youtube.com/watch?feature=player_embedded&v=...