Great Awakening

The Great Awakening is an event that occured twenty years before the start of Fallout. It is mentioned only in Chris Avellone's Fallout Bible.

Background
The Great Awakening refers to the mentioned-only event in which Jonathan Faust talked the crazed Pit Venom victims into believing that the Great Snakes had spared their lives and to fight for his cause after emerging from the Pit and having pit vipers attack what was left of his group of Vault survivors, leaving forty or so of them "half-crazy" from the venom. This led to the creation of the Viper clan.

Behind the scenes
"Great Awakening" may also refer to several periods of religious revival in American history. See Wikipedia: Great Awakening.