The events at Mariposa are not so black and white Andaius. The ancestors of the BoS executed a bunch of psycho murdering a-holes who were conducting experiments on people with biological weapons.
Were they justified or not? That's a bit of a morally grey area imo, but I certainly shed no tears for the scientists who were doing atrocities that would make Caligula's ghost cringe.
Nonetheless, the BoS was built by soldiers with the creed of soldiers. Even in the original Fallouts, the BoS isn't half as bad as people make them out to be; their reputation as puppy killers is derived from superstitious people who know nothing about them since they were mainly isolationists at the time. The Enclave however was born from beaurocrats and politicians, reason enough for them to be a plague to anything outside their little organization.
I have no idea who created the Enclave, if it was a specific group within the government or a secret government organization involving the upper tier of the Executive and Legislative branches from the get go. Not that the majority of the government wasn't apecrap insane already anyway... :blink:
But out of all the bungholes within the government at the time, the ones who eventually would found the Enclave were the very worst of ibherently gifted bungholes.
@Expresate: Don't bother with someone like that; besides, he doesn't even realize that he's already pretending to be an american as all Fallout characters were born inside the US anyway.