Nationalism in 19th-century Europe played a critical role in shaping political landscapes, as it emphasized the importance of a shared national identity, culture, and language among people within defined borders. Emerging in the aftermath of the French Revolution, nationalism motivated movements for independence and unification, as seen in Italy and Germany. Nationalist sentiments often fueled conflicts and rivalries, contributing to the instability of empires, such as the Austro-Hungarian Empire. It was a driving force behind both the unification and disintegration of states, ultimately laying the groundwork for World War I and shaping modern national boundaries.