Nationalism — an idea destined to have an enormous influence in the modern world — was another radical idea that gained popularity in the years after 1815. Early nationalists found inspiration in the vision of a people united by a common language, a common history and culture, and a common territory.

In the early nineteenth century, such national unity was more a dream than a reality as far as most ethnic groups or nationalities were concerned. Local dialects abounded, even in relatively cohesive countries like France. Moreover, a variety of ethnic groups shared the territory of most states. Over the course of the nineteenth century, nationalism nonetheless gathered force as a political philosophy. Advancing literacy rates, the establishment of a mass press, the growth of large state bureaucracies, compulsory education, and conscription armies all created a common culture that encouraged ordinary people to take pride in their national heritage.

In multiethnic states, however, nationalism also promoted disintegration. Recognizing the power of the “national idea,” European nationalists — generally educated, middle-class liberals and intellectuals — sought to turn the cultural unity that they desired into political reality. They believed that every nation, like every citizen, had the right to exist in freedom and to develop its unique character and spirit, and they hoped to make the territory of each people coincide with well-defined borders in an independent nation-state.

This political goal made nationalism explosive, particularly in central and eastern Europe, where different peoples overlapped and intermingled. As discussed, the Austrian, Russian, and Ottoman central states refused to allow national minorities independence; that suppression fomented widespread discontent among nationalists who wanted freedom from oppressive imperial rule. In the many different principalities of the Italian peninsula and the German Confederation, to the contrary, nationalists yearned for national unification across what they saw as divisive and obsolete state borders.

Between 1815 and 1850, most people who believed in nationalism also believed in either liberalism or radical republicanism. A deep belief in the creativity and nobility of the people linked these two concepts. Liberals and especially democrats saw the people as the ultimate source of all government. Yet liberals and nationalists agreed that the benefits of self-government would be possible only if the people were united by common traditions that transcended local interests and even class differences. Thus the liberty of the individual and the love of a free nation overlapped greatly in the early nineteenth century.

Despite some confidence that a world system based on independent nations would promote global harmony, early nationalists eagerly emphasized the differences among peoples and developed a strong sense of “us” versus “them.” To this “us-them” outlook, it was all too easy for nationalists to add two highly volatile ingredients: a sense of national mission and a sense of national superiority. As Europe entered an age of increased global interaction, these two underlying ideas would lead to aggression and conflict as powerful nation-states backed by patriotic citizens competed with each other on the international stage.