Captain Samantha Carter first appears in "Children of the Gods", the pilot episode of "Stargate SG-1", as a United States Air Force Captain who joined the fictional SG-1 team under the command of Colonel Jack O'Neill. After being promoted to Major in Season 3, Carter remains O'Neill's second-in-command until her promotion to lieutenant colonel early in Season 8, at which point she assumes command of the SG-1 team and O'Neill is promoted to Brigadier General in order to lead Stargate Command. Between Seasons 8 and 9 of SG-1, following the defeat of the Replicators and downfall of the Goa'uld system lords, she accepts a position as Head of the Stargate Research and Development Programme, based in Nevada. Engaged in deep-space research the Ori emerge, upon her return to Earth she is reassigned to SG-1, now under the command of Lieutenant Colonel Cameron Mitchell. Following the defeat of the Ori in "Stargate: The Ark of Truth", Carter is promoted to full colonel and appointed as commander of the Atlantis expedition early in Season 4 of "Atlantis". Carter is later given command of the Daedalus-class ship, the "George Hammond".