As it happens, I tangentially addressed communism in my last post:
"The VIII-XIX century were dominated by ~4 'large' currents: enlightenment humanism; conservatism (sharing the same methods - rationality - and ultimate goals with enlightenment); nationalism; utopian ideologies.
Edmund Burke, Joseph de Maistre - and Metternich - were conservatives - their goals and methods were similar to the enlightenment's. The difference? They believed continued monarchy was the way to progress and peace (the experience of the french revolution scaring them away from liberal democracy).
Conservatism is called sometimes counter-enlightenment - but it shared most of its content with enlightenment humanism.
Nationalism and its utopian ideologies, on the other hand - these WERE counter-enlightenments. They rejected reason itself as a legitimate path to reach valid conclusions about society, governance, etc. Rather, what 'felt' right was the way to go.
As for the results of these - communism, fascism, etc.
As for the deaths due to the wars/atrocities linked to communism - they are included in the numbers and analysis I posted.