The Barton Foundation planned to use this large army, fitted with new mobile suits, to carry out their plans of conquest. Dekim Barton was the head of this rebel force, and had installed his granddaughter, Mariemaia, as figurehead. Mariemaia is the daughter of his daughter, Leia Barton, and the late Treize Khushrenada. This lineage was used as a way to rally supporters, and the Mariemaia Army claims to hold to Treize's ideals.
They kidnapped Relena, the vice foreign minister, and took over the Presidential Mansion on the Earth. The Gundam Pilots fought the Mariemaia Army, and were finally able to breach the mansion's security. Inside the mansion, Dekim tried to shoot Relena, but Mariemaia stepped in the way, took the bullet, and was left parapalegic. Dekim shown no remorse for shooting Mariemaia, and one of the soldiers in the room shot and killed him, and apologised for betraying "His Excellency" Treize Khushrenada. Mariemaia no longer desired to continue the war, and the Mariemaia Incident ended, with the army laying down its arms, and dissolving.