From the Enhanced Edition Official Rulebook
During the Civil War, the Ironclad project produced the USS Monitor, a heavily armored ship that took part in a decisive naval battle against the CSS Virginia. Less than a century later, the ongoing Ironclad project produced another success: the Personal Armament Exo-Chassis YS-1200. The suit allowed one soldier to do the work of an entire squad and operated in an elite battalion during World War II. 50 years later, a new armored suit was developed: the Personal Armament Exo-Chassis YS-1300T. When the government began its Freedom Five initiative, Lt. Tyler Vance was selected to operate the Bunker suit for the first time as part of a non-army campaign. Thus, Bunker became the second member of the Freedom Five, joining Legacy in the fight against the villains who threatened the world.