On C.E. 70 June 14th, ZAFT forces invaded Lagrange Point 4 and laid siege to Republic of East Asia's stronghold Nova asteroid base. While the initial battle broke out around the asteroid base, the fighting escalated to surrounding colonies. Eventually the civilian populations of these colonies had to be evacuated.

On July 12th, the last of the Republic forces retreated from Nova, ending the month-long siege, and ZAFT successfully taking control of the asteroid base. After the battle, it was decided to move the asteroid to Lagrange Point 5, closer to PLANT homeland. During the transport, the Earth Alliance attempted to retake the asteroid, but were defeated by the ZAFT escort fleet, of which Miguel Aiman was part of. After Nova was moved to L5, the asteroid was converted into a space fortress and renamed Boaz.

Frustrated by their repeated defeat in the war, the Atlantic Federation government re-examined and eventually approved the G-project proposed by Admiral Halberton as a mean to break the stalemate and gain an advantage over ZAFT.

Meanwhile the patriarch of Orb's Sahaku clan, Rondo Gina Sahaku, is frustrated by Orb's own lack of progress to make Mobile Suits superior to ZAFT's machines, stalling his own ambitions. He devised a plan to acquire Atlantic Federation's advanced technology by partner with the them to co-develop Mobile Suits. With his assistance, work began on these top-secret weapons that the Atlantic Federation hoped would reverse the course of the disastrous war, while Sahaku is staking his ambitious plan of domination with these new technology