It was followed in 2010 by Supreme Commander 2. The Seraphim's human cohorts didn't like that too much, formed the Aeon Illuminate and pretty much told the rest of the galaxy to join or die. Unfortunately, the local Imperial military commander overreacted, and caused the genocide of the Seraphim with a bioweapon.
See, the Seraphim had a peaceful and advanced society, complete with a quasi-Buddhist philosophy they called The Way which they shared with the human colonists. The next and probably biggest nail in the coffin of the Earth Empire is the formation of the Aeon Illuminate, that got founded when human colonists on one planet ran into alien intelligent life, the Seraphim. So Brackman and a group of followers rebel, set up their own country - the Cybran Nation - and start waging a guerrilla war to liberate their fellow symbionts. Unfortunately, the Earth Empire treats the symbionts more like slaves than real people which is something the symbionts and their father figure Brackman don't particularly like. The first nail in the coffin of this golden age is the symbionts, humans enhanced with cybernetic implants - the chief figure having had their brain merged with an advanced AI computer in a process patented by Dr.