One of the great successes of the Soviet regime was to promulgate and, eventually, to impose on the world its own ideological understanding of how political systems should be classified. Lenin reduced them essentially to two polar opposites, socialism and capitalism, a dichotomy preserved by Stalin until the 1930's. According to this scheme, capitalism, also known as imperialism, included in its purview liberal, social-democratic, and fascist regimes, as well as National Socialism. A different scheme emerged in the 30's to accommodate the new Soviet policy of building "popular fronts." Now the spectrum ranged from socialism—that is to say, the Soviet Union—through the bourgeois democracies (liberal and/or social-democratic), to, finally, fascism. Grouped together under the last category were Nazism, Mussolini-type fascism, the authoritarian regimes of Spain, Portugal, Austria, Hungary, Poland, and so forth, and extreme right-wing factions in liberal societies.
Whatever the specific typology, Nazism in these schemes was erased as a category unto itself, and attached definitively either to capitalism or to right-wing fascism. It became the absolute incarnation of the Right, while Soviet socialism represented the absolute incarnation of the Left. In this way Nazism and Communism took their respective places in the great magnetic field of 20th-century politics.
To appreciate the sleight of hand involved, one need only recall that to an earlier generation of historians, it had been perfectly clear that both Italian fascism and German Nazism had socialist roots. Thus, Elie Halévy’s classic History of European Socialism (1937) devotes a chapter each to the socialism of fascist Italy and the socialism of Nazi Germany. (The latter, indeed, had explicitly declared itself to be anti-capitalist.) Then there is the no less compelling scheme proposed as early as 1951 by Hannah Arendt, who spotlighted the essentially consanguineous nature of Nazism and Communism that I remarked upon at the outset, and divided these two representatives of modern totalitarianism from liberal and authoritarian regimes alike.
So great was the triumph of the Communist definition of reality, however, that even today it remains deeply embedded in historical consciousness. French high-school and university textbooks, for example, still "read" the political spectrum from Left to Right, going from the Soviet Union on the Left, to the liberal democracies (with their own Lefts and Rights), to the various fascisms (German, Italian, Spanish, and so forth). This is but an attenuated version of what might be called the Soviet Vulgate.
(Alain Besançon, "Forgotten Communism," Commentary [January 1998]: 24-7, at 26-7 [italics in original])