In the nineteenth century, Europe underwent an economic, political, and social transformation. The spread of capitalism increased the continent's wealth and dynamism, which in turn fostered the diffusion of European culture and civilization across the globe. The forces that were driving Europe to the height of its power, however, were also generating social and political turmoil. Dissatisfaction with the reigning liberal order grew over the course of the nineteenth century. Ultimately, the practical consequences of unfettered capitalism – dramatic inequalities, social dislocation, and atomization – generated a backlash against liberalism and a search for ideological alternatives. As one of the great observers of the liberalism of the era, L. T. Hobhouse, noted, if “The nineteenth century might be called the age of Liberalism …its close saw the fortunes of that great movement brought to its lowest ebb.”

The most important challenge from the left came in the form of Marxism, which during the second half of the century gathered enough adherents to spawn its own political movement. By the time of the Second International, (1889–1914), orthodox Marxism had become the dominant doctrine within most socialist parties. The most distinctive features of this orthodox Marxism were historical materialism and class struggle, which combined to produce a view of history as being propelled forward by economic development and the ever-sharpening class conflict generated by it.