How did nationalism play an impact in the first World War

Nationalism led to the desire of countries with strong self-identities to unite and attack other countries.

Explanation:

Nationalism is an ideology and movement that promotes the interests of a particular nation especially with the aim of gaining and maintaining the nation's sovereignty over its homeland.

Answer: was through the assassination of Archduke Franz Ferdinand, who was the heir to the throne of the Austro-Hungarian Empire.

Explanation: Many oppressed Slavic groups in the Austro-Hungarian Empire wanted to form independent nation states.