During the expansion of industrial capitalism in Europe, attempts to maintain or eradicate restrictions on political rights and economic opportunities generated minority and class conflicts at home; efforts to secure protected markets abroad in lieu of developing internal markets generated imperialist conflicts abroad. These conflicts generated tensions that produced, in 1914, a massively destructive regional war.

During the interwar years, struggle between left and right in Europe was carried on in a more or less continuous round of violent strikes, demonstrations, riots, and street fighting, as well as coups, rebellions, and revolutions. As a result, over the course of the nineteenth century, the domestic and international relations of European states became increasingly polarized.

Before that, Europe had developed, over the course of several centuries, a three-fold social class structure: an upper class of noble landowners and administrators, a peasantry, and, set off from both of these by law (e.g., in Germany) or by custom (e.g., in England and France), an urban commercial and professional middle class.