Why did the assassination of Archduke Ferdinand trigger the war in Europe?

This widespread nationalism is thought to be a general cause of World War I. Nationalism played a specific role in World War I when Archduke Ferdinand and his wife were assassinated by Princip, a member of a Serbian nationalist terrorist group fighting against Austria-Hungary's rule over Bosnia.

Explanation:

basic principles: federalism, separation of powers, checks and balances, judicial review, representative democracy, limited government, rule of law, individual rights and responsibilities, consent of the governed, majority rule, popular sovereignty, equal protection.