This achievement asks that you complete each of the missions for the RESISTANCE forces on the WINNING TEAM, including the What-If missions. These are:
Day 1: Getting Answers
Day 2: Breakout
Day 3: Chen's Plans
Day 6: Black Box
Day 7: Attack on CCity
Day 8: Airborne
What-If: Operation Babel
What-If: Critical Reaction
Must be completed on a single character, but can be unlocked online and offline, in Solo, Co-op, or Versus. Simply select Campaign from the main menu, select your mission of choice, and tweak the settings to your liking. Difficulty is unimportant. Missions you have won will be displayed with the round checkbox next to them filled in.