The only salvation this tortured planet and its people have. Without us, humanity is sure to perish.

The Brotherhood of Steel is a quasi-religious technological organization operating across the ruins of post-war North America, with its roots stemming from the American military and the government-sponsored scientific community from before the Great War.
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The Brotherhood of Steel was founded by Roger Maxson, a captain in the United States Army. Led by Colonel Robert Spindel, Maxson was part of a team sent on January 3, 2076 to monitor progress at a West-Tek facility in California, which was conducting research on behalf of the American government. On January 7, 2077, all West-Tek research and personnel – Maxson and his team included – were relocated to the newly constructed Mariposa Military Base in an effort to enhance security.

Brotherhood of Steel Information[fallout.wikia.com]