The development of nationalism in the 19th century was fueled by various factors, including the rise of romanticism, industrialization, and the impact of the French Revolution. Romanticism emphasized national identity, culture, and shared heritage, fostering a sense of pride and unity among people with common backgrounds. Industrialization transformed economies and created social changes that often led to the emergence of nation-states. The spread of ideas about self-determination and democratic governance inspired various ethnic groups to seek independence or autonomy, ultimately leading to the unification of nations like Italy and Germany and the decline of empires.