Nationalism

Intense nationalist sentiment drove peoples to identify with their nations and to despise rival nations. French nationalists hungered for revenge for the loss of Alsace-Lorraine in 1871. German nationalists celebrated unification and expansion. Slavic nationalists in the Balkans (especially Serbs) sought to unite South Slavs in a single state. Polish, Czech, Hungarian, and other ethnic groups within the multi-ethnic Austro-Hungarian and Ottoman empires demanded self-determination. Pan-Slavism connected Russian and South Slav aspirations. These competing nationalisms made compromise increasingly difficult.

How MAIN actually works: The MAIN acronym is more than a memory device. The four factors functioned as an interlocking system. Imperialism produced competition; competition produced alliances; alliances produced militarism; militarism intensified nationalism; nationalism made conflicts harder to resolve diplomatically. A complete answer about WWI causes shows how these four reinforced each other.