'For the people' is one of the ending achievements, and is related to the choice you can make at the end of the final mission, Suez.
To unlock 'For the people', when you plant the C4 and are dangling with Irish and Hannah, you must choose to send Irish on the suicide mission.
This will cause the game to play out, and at the end you will receive this achievement as well as Irishs' dog-tag and the related assignment.