You get this achievement on the 11th level WMD. You need to get to the Comms station without dying or having the squad die. Set the difficulty to recruit just to be safe.
You start off piloting a Blackbird, once you take control of the co-pilot you direct the squad on the ground. It's pretty straightforward just follow the waypoints and listen to the games audio, the pilot will tell you exactly what to do. After your squad clears the safehouse you retake control of the co-pilot and you will need to direct your squad up north, there will be two hostiles. Select them with your target reticule or they will kill you.
Next when the pilot tells you to send your squad to the barracks only direct them a few feet from where they are. Once you move them the pilot tells you a large patrol is heading their way. With your target over your squad press your melee button your squad will hide and the patrol will pass.
After that clear out the barracks then direct the squad to the next two waypoints and the achievement is yours.