So I'm on my third playthrough of the campaign for achievement purposes and I have failed again at getting the mission "Piercing the Shroud" which is apparently one of the missions given by Horner?
I can't figure out what I'm doing wrong and if I'm supposed to do missions in a certain order to get the mission but it's reeeaaallly pissing me off not being able to get the achievements for it. Anyone know how to get it?

You need to destroy a science facility (bottom right corner) and pick up the documents that drop in that mission where you control the Odin.

I believe this mission is the secret mission you unlock during the Odin mission where you have to capture the broadcast towers. Check for a civilian building along the edge of the map labelled as being in control of rebels or refugees. You have to manually tell your units to destroy it, then you will pick up an item that unlocks the mission.

Get the secret documents during the mission 'Media Blitz'. Destory a build at the bottom right of the map (not an enemy building) and grab the documents.

 Can I unlock the mission if I redo the Odin one or is it something I have to do the first time through?
Also, thank you all very much for the help!

You need to use the Odin's barrage attack or something like that. You can't just click on it.

" You need to use the Odin's barrage attack or something like that. You can't just click on it. "

" @The_Laughing_Man: Oh I didn't know that. I tried to attack it with a bunch of troops and the Odin and nothing happened.  "