Season eight of Stargate SG-1 began airing on July 9, 2004 on the US-American Sci Fi Channel. The eighth season concluded on February 22, 2005, after 20 episodes on British Sky One, which overtook the Sci Fi Channel in mid-season. The eighth season begins with the SG-1 team trying to revive Colonel Jack O'Neill after the events of the seventh season. At the end of the two-episode season opener, O'Neill is promoted to Brigadier General and assumes command of Stargate Command, while Samantha Carter is promoted to Lt. Colonel and assumes command of SG-1. The season arc centers around the growing threat and seemingly final defeat of the Goa'uld and the Replicators, races who had been introduced in the first season and third season of the show, respectively.