Camp Eureka was a United States Army base built in the mid-1940s on the location that would later become of the town of Eureka, OR Like its modern counterpart, it was a Top Secret DoD installation with military oversight of 'the eggheads' and their projects. The timeline of Season 4 was a result of the five characters who time-traveled back to 1947 Camp Eureka having an immense impact on the course of events.