The Missouri compromise was nullified by the Kansas-Nebraska act. This act allowed the people in each state to determine whether or not slavery would continue within their state.
Abolitionist John Brown was executed because of his attempt to seize the arsenal at Harper's Ferry. John Brown led the Harper's Ferry raid.
Bourgeoisie? Not sure, though. But Marx used to call them that so...
The cholera epidemic. The others were factors, but not as serious.