The Chimera was built by the combination of S.H.I.E.L.D. and was powered by an extremely powerful energy source know as a Terrigen Crystal. On the day of A-Day in which the Avengers were to introduce it to the public the mercenary Taskmaster attacked the event with the goal of stealing Terrigen Energy reactor. While the Avengers foiled Taskmasters attempt, the Chimera was destroyed when Captain America smashed the reactor in hopes of preventing a massive Kree Sentry from rising out of the San Fransisco bay and potentially killing millions. While successful the explosion destroyed almost the entirety of the city and released a mist that transformed any exposed to it into superhuman beings. The Avengers were also disbanded thanks to the testimony of Bruce Banner himself.
Five years the Chimera would lay abandoned before The Avengers were reunited and managed to make it their base of operations again in their fight against A.I.M.