During the cold war the government wanted to have super powered humans instead of nukes and bombs. To that end the hired Dr. Jacob Krigstein. Krigstein was an imaginative genius who could create super powered beings but when the cold war was over america didn't care about the super hero program since they where the last super power. However the good doctor didn't like that idea. Years later after making a team full of super powered beings he decided to send them after the recently born Jenny Quantum. she was the spirit of the 21st century and with her Krigstein could influence the next 100 years.
The Americans where sent to the hospital Quantum was born in and a few of them killed and raped everyone there. The Doctor however gets her first and then the rest of the Authority show up to back him up. The two forces fight but in the end the Americans take Jenny. Later Engineer and the Doctor go to a secret base and discover the secrets behind the Americans. Soon the Americans make a mass invasion on different cities and the Authority split up to stop them but in the end Swift makes a deal with Krigstein. In return for getting Jenny he can live on the Carrier and help them make a new world. He agrees. Meanwhile, most of the Americans were massacred by the others Authority members.
Pretty much all of the Americans with any amount of screen-time are "evil versions" not only of the Avengers members but their membership includes also evil versions of Nick Fury and SHIELD agents, Fantastic Four, X-men (reversing their genders and changing the "X" by"Y" motif), Daredevil, Spider-man among others.
The core group of the Americans was composed by the more traditional Avengers membership: Commander is Captain America, Tank-Man as Iron Man, Storm-God is a Thor knockoff, while Titan refers to Hank Pym and Hornet to his ex-wife Janet. Another unnamed members are a look alikes of Hulk, Vision, Wonder-Man Quicksilver, Scarlet Witch, Black Panther, et all.
The Americans only would reappers as dreams projections of Chimera, protecting him after the End of the world striked on the Wildstorm universe.