NSC was founded by neo-Nazi Chris Hood (bottom right) after he was kicked out of Patriot Front.
"NationalSozialistischer Deutscher Arbeiter"
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"National Socialist German Worker"
SIEGE is a collection of writings by neo-Nazi James Mason that essentially acts as a how-to guide for kicking off the Race War. It's widely held in high regard by 'accelerationist' white power groups, like the aforementioned Atomwaffen Division.
But here we see them still using it.