As the long history of international solidarity movements throughout the nineteenth and twentieth centuries demonstrates, emotions fostered a sense of common belonging in the name of so-called universal brotherhood, solidarity of peoples, or defence of human rights. Investigating exemplary political mobilizations in Europe that transcended national borders, such as the Philhellenism of the 1820s, the solidarity movements during the Spanish Civil War (1936–1939), and against the Chilean dictatorship in the 1970s and 1980s, helps to illustrate the strengths but also the limits of these feelings. These movements, which shaped and were shaped by individual and collective emotions such as compassion, fear, and anger, but also enthusiasm and hope, developed a complex relationship with patriotism and universalism, as well as with the state and other political institutions.