How did John Brown's raid contribute to the start of the American Civil War?

 Abolitionist John Brown lead a small group on a raid against a federal armory in Harpers Ferry, Virginia, in an attempt to start an armed slave revolt and destroy the institution of slavery.

Explanation:

an aneroid barometer is different from a mercury barometer in that it provides readings that increase as air pressure increases.

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answer; if congress didn't act on certain requests;