User blog comment:Martolives/Mass Relays/@comment-2079715-20120402103043/@comment-4871521-20120402104605

Well, if they didn't, they would have been forced to go the hard way. (Witch they were forced to in ME3 by arriving just using FTL-drive.) As Vigil said in ME1: "Our leaders were dead before we even realised we were under attack. They sized control of the Citadel; the hub of the relay-network, and through it; the mass relays. / Each system were cougth of from each other. Easy prey for the Reaper fleet." Thats what they needed Sovereign to open the portal, so they can start harvest organic life without any major resistance or setbacks, as seen with the protheans, and the other ones who came before. PS Mind the language by the way ;)