Question

How did imperialism and nationalism lead to WW I and what part did they play in the war?

Answer 1

Hint: World War I (WW I) began in 1914 and lasted four years ending in 1918. Though the assassination of Archduke Franz Ferdinand was the immediate reason leading to the declaration of war, there were many other reasons that initiated the WW I including factors of imperialism and nationalism.

Complete answer:
Imperialism is a system where a powerful nation seizes, controls and exploits territories beyond its borders. It acted as one of the important causes of World War I. Prior to World War I itself, several European nations were imperial powers. Great Britain was the most dominant imperial power even before WWII. France, Germany, Spain, Portugal etc were the major global imperial powers during these times. Imperialist nations assert control over other territories through infiltration and annexation, political pressure, military conquest or war. Competition for new territories and possessions as well as imperial rivalry increased tension between major European countries and became a reason in the outbreak of World War I.
Nationalism was a power in early $20^{th}$ century Europe and acted as a major cause of World War I. Nationalism is an extreme form of patriotism and devotion to one’s country. Placing its interests above those of other nations, nationalists exaggerated the importance of their own country.
Nationalism was a product of the rise of involvement of people in government, the formation of empires and periods of economic and social transformations. Wars, imperial conquests, political discourses, rivalry, newspapers and popular culture contributed greatly to the pre-war nationalism.
Expansion of the British empire, German nationalism resulting from German unification, Serbian nationalism for a Greater Serbia etc caused the increase of nationalist sentiments and many important events in World War I.

Note: The two Moroccan crises, as well as German imperial expansions, are examples of events that happened in World War I as a result of the influence of nationalism and imperialism. The conflicts over alliances, European expansionism, and German millenarianism also had roles in the emergence of World War I.