Continue until you reach the end of the section. Before pressing up to complete and move to the next section, check the dumpster beside the building across the exit to find this COG tag.
Section 2 – Riverwalk District
Once you've reached the outpost, go past the fountain and enter the narrow alley. Follow it and you should spot the COG Skull on the wall. Look on the ground nearby, near the wall to find the COG Tag.
After finding the declassify mission skull, smash the door open and check the alley to the right. You'll find a COG skull on the wall. Go past it and head to the dead-end corner of the alley, past the bloodstains on the ground to find this COG tag.
Section 4 – Great Hall
You can collect the COG tag in front of the statue in the middle fountain.
Continue until you reach a large room with turret emplacements. The COG tag is located in the middle of the room, in front of the turret.
Continue until you reach the exit point of this section. Before completing the section, you should check the small room to the right of the area's exit door. You'll find a corpse with a COG tag there.
The COG tag is located inside a warehouse where there are stacks of containers and crates. (this is right after the area where there are several serapede eggs you can destroy) Proceed while keeping to the left and you'll find a COG skull past Archive shelve XIII. In the dead-end there with a corpse and a dog tag.
After clearing the area, your team will gather by the exit. Before regrouping with them, check the wall to the right of the stairs leading to the exit. You should find a COG skull there. Go further to the right of that skull to find a corpse with a COG tag.