This is a story related achievement
You get it for completing story mission:
*** Spoiler - click to reveal ***KILLING KANE (mission number 14)
I found this mission quite difficult. You have to destroy 3 bases while killing enemy mechs, tanks and helicopters. 3rd base is the hardest to destroy because it has boss mech in it along with other enemies and you are already hurt from destroying first two.
As with all other missions, you can restart them at any point, if you feel you have taken too much damage. No checkpoints during the missions though.
Always make a manual save before going on mission or after successful mission.