Answer:
One of the best examples of nationalism causing tensions in Europe is the First World War. In the years leading up to the war, many European nations experienced a surge of nationalist sentiment, particularly in the Balkans. This led to increased tensions between different ethnic groups and calls for independence, particularly from the Austro-Hungarian Empire. The assassination of Archduke Franz Ferdinand of Austria in 1914, by a member of a nationalist group, sparked a chain reaction of events that ultimately led to the outbreak of war. Nationalism played a significant role in the causes of the First World War and in the tensions between European nations.