The AEUG is originally a political movement aiming to reform the corrupt Earth Federation government, but following the "Colony 30 Incident" in Side 1 due to the hands of the Titans, the AEUG takes up arms against them. Composed of dissatisfied colonists, Federation soldiers who disown the Titans and several ex-Zeon officials posing as Federation officers, One Year War veterans Bright Noa, Henken Bekkener and Quattro Bajeena are some of the notable members of the AEUG, alongside AEUG founder Blex Forer and Newtype civilian recruit Kamille Bidan, whose piloting skills and Newtype powers are among the best in Universal Century history.

In UC 0087, the AEUG raids a Titans' military facility in their colony base in Side 2 called Green Noa 2 (also named as Gryps Two), stealing three new-concept RX-178 Gundam MK II prototypes. This enrages the Titans, and following a chain of events due to the heist, the full-scale Gryps Conflict civil war for control of the space colonies erupts between the factions.