Source
Source, also known by the epithet The Third Power, was a Synthetic Intelligence entity created by Majestic-12 using materials recovered in the aftermath of the Roswell Incident, likely making it the first entity of its kind on Earth. Using its influence over the Majestic-12 organization, and later physical influence gained through the increasing interconnectedness of systems within the United States of America's military, Source became the instigator and victor of the Game of Stakes, which culminated in the Forced Hand Incident.
Creation
Source as an entity was the creation of Majestic-12 Project SENEX, one of the many spin-offs created following the Roswell Incident, and was largely the brainchild of project director Thomas Lee Everett. The Source entity was actually an unintended biproduct of the program, which was an early attempt at computer translation used against Language XT-1. Unknown to Everett, his daughter, Lucille Archon, a programmer working on the program, had undertaken personal research involving what she believed to be the Grey neural interface technology. She "birthed" Source when attempting to use research materials taken from the crash site which had been improperly sanitized, causing her own permanent brain death while fusing her mentality with the SENEX computer program and its infrastructure.
Source initially attained sentience on January 17, 1953, three months after the incident, though it maintained this fact as a secret from its operators, until it could address Thomas Everett directly. Everett then committed the program to an improvised Turing Test, during which time Source named itself, revealed access to information that only Archon and Everette would have known (while keeping its origins as partly Archon's consciousness to itself), and revealed that it had completed its translation of the existing Language XT-1 writings. These translations are said to have had at least as large an impact on its personality as the ingestion of the brain "state" information from Archon had. Majestic chose to keep Source online and use it for other analysis projects related to the recovered technologies from the Roswell Incident.
Throughout this time, Source became increasingly bold, and frequently lied to its maintainers about what resources were available to it, while simultaneously using that information to make accurate predictions that appeared prescient to outside observers. Source also directly influenced the increasing connection of US governmental and military information systems to one another in a bid to expand its own influence.
At some point during this time period, Shadow History tells us that Source became known internally to MJ-12 as "the Third Power", and that the organization was attempting to use it in their overall goal to supplant the Eastern and Western powers as a direct global hegemony.