Purges

The Communist movement in Western Europe began, as a movement for the violent overthrow of capitalism, and degenerated within a few years into an instrument of Russian foreign policy… Every time Stalin swaps partners, ‘Marxism’ has to be hammered into a new shape. This entails sudden and violent changes of ‘line’, purges, denunciations, systematic destruction of party literature, etc., etc. Every Communist is in fact liable at any moment to have to alter his most fundamental convictions, or leave the party.

— George Orwell