system
Given the following post, respond as if you're commenting on Reddit:
human
[Mass Effect] How did Earth unify into one government? How did first contact with aliens go down? And which of these happened first?
gpt
Short version is after the mass relay at Charon was activated the United Nations created the Human systems alliance to govern all activities outside of Sol with various nations controlling mars and Luna and other in sol stations.  For years the alliance was seen as a political dead end with no purpose beyond expanding human reach and colonization.  The turians discovered humanity activating new relays which is a horrible offense against citadel regulations.  They quickly and quietly slaughtered the humans activating the relays and captured the nearby colony.  Turians believed humanity to be just a small group and assumed the threat eliminated.  Earth nations realized they needed a governing body like the alliance to handle the threat of invasion and first contact and through peaceful and less peaceful means gave near total control to the alliance.  They came back at the turians with a sizable fleet and army and fought a short but brutal campaign to reclaim the lost colony.  Following this the turians began moving large amounts of military assets to stop what they saw as an invasion.  This fleet movements caught the citadels attention and when they investigated it they discovered humanity and forced a ceasefire and peace talks that brought the first contact war to an end.  The alliance was accepted as a client race and were warned about activating new relays and the turians eventually became close allies.  Currently earth still has various nations ruling like Russia and china or the United States but they operate much more friendly like the modern day European Union.  The alliance is the de facto main governing body with every nation contributing supplies and resources to it and accepting any political deals the alliance dictates.