The proletariat should not ignore peaceful methods of struggle — they serve its ordinary, day-today interests, they are necessary in periods of preparation for revolution — but it must never forget that in certain conditions the class struggle assumes the form of armed conflict and civil war; there are times when the interests of the proletariat call for ruthless extermination of its enemies in open armed clashes. This was first demonstrated by the French proletariat in the Commune and brilliantly confirmed by the Russian proletariat in the December uprising.

"Lessons of the Commune", Collected Works, Vol. 13.