The Earth Alliance is the group of anti-ZAFT superstates on Earth in the Cosmic Era timeline. It is made up of four political entities: the Atlantic Federation, the Eurasian Federation, the Republic of East Asia and the South African Union. The Earth Alliance also conquered the PLANT-friendly United States of South America, which are now engaged in a revolution to regain their independence. The Earth Alliance was officially founded as a result of the Alaska Declaration on 7 February CE 70. The combined military forces of the Earth Alliance are called OMNI Enforcer, but are more frequently simply called the Earth Military (Chikyuu Gun). The Alliance is headed by a moderate Secretary-General, but the real rulers of the Alliance are Blue Cosmos and its LOGOS benefactors.
The Earth Alliance and ZAFT started war on 11 February CE 70 after the EA's predecessor, the United Nations was wiped out by a terrorist attack in the Tragedy of Copernicus on 5 February. On 14 February, the Alliance used nuclear weapons to destroy the PLANT colony at Junius Seven, in what became known as the Bloody Valentine Incident.
Unlike the Earth Federation of the Universal Century era which was a relatively unified body, the Earth Alliance is more of a loose international military confederation of entities that are often working at cross purposes to each other. It is not uncommon for each of the factions to not reveal the key workings of their weapon and armor technologies with their erstwhile allies - when the Atlantic Federation battleship Archangel docked at the Eurasian military base Artemis, the commander attempted to acquire by force both the ship and its GAT-X105 Strike mobile suit contingent in order to acquire the secret behind their designs. Later, when the Alliance headquarters, JOSH-A in Alaska, controlled by the Atlantic Federation, was mostly abandoned as a trap for ZAFT's invasion forces, the token defense force left behind as "bait" (completely unaware of the trap) consisted almost entirely of Eurasian troops.
The Alliance developed several important military innovations during the war: the second-generation Mobile Operating System, Phase Shift armor, Lightwave Barrier, beam weaponry and the Mirage Colloid stealth system.
In the wake of the Junius Seven colony drop disaster (Operation: Break The World by the Coordinator terrorists) in CE 73, the Earth Alliance declared war again on ZAFT, on the grounds that the drop represented the true intentions of the Coordinators toward Naturals, and the EA intends to wipe out the PLANTs and with them the Coordinators once and for all. However, the initial attempt to destroy the PLANTs with nuclear missiles resulted in a disastrous defeat when ZAFT's Neutron Stampeder destroyed an entire Alliance fleet with a single shot.
Popular support for the Alliance was weakened after PLANT Chairman Gilbert Dullindal exposed the LOGOS, the organization behind the Alliance's Blue Cosmos rulers and vowed that ZAFT will destroy LOGOS and Blue Cosmos once and for all.