After the death of Lenin, the Comintern increasingly saw its activities subordinated to Stalin's changing conceptions of the interests of the Soviet state. Never the source of flexible or progressive developments in terms of marxist theory, the Comintern was, however, forced by the advent of Hitler's regime in 1933 to abandon its sterile ultra-sectarian policy of the previous decade. This had been marked by a damaging excoriation of all social democratic parties as ‘social fascist’. The Comintern's new direction culminated in the adoption of Popular Frontism at its Seventh Congress in 1935. The Popular Front strategy, though, was not adopted solely with the short-term aim of defeating fascism. Rather, Popular Frontism was seen also in terms of using bourgeois democracy's institutions to ‘prepare the masses for the overthrow of the power of capitalism and to achieve proletarian democracy’.

Such talk of capitalism's overthrow did not seem far-fetched in the context of contemporary developments. In particular, the New York stock exchange crash in 1929 had been taken by European marxists as evidence of the impending collapse of the capitalist mode of production; fascism, in turn, was seen as representing a last-ditch effort to stave off this collapse by suppressing the working class. Although in this fascism had proved distressingly effective, it did represent, in marxist terms, a response to capitalism in crisis. In Spain, as in the rest of Europe, the looming threat of fascism had for some years been exercising the minds of marxists concerned to analyse the phenomenon and formulate a viable response.