Answer :

Nationalism is the act of perceiving our own nation as better/superior than other country. During world war I, Germany initiated their war due to this feeling of superiority toward other European nations, and perceived their country as the rightful ruler of the European continent.
LREH

Answer:

Because the Nationalism was an intense form of patriotism.

Explanation:

Those with nationalist  tendencies celebrated the culture and achievements of their own country and placed it's  interests above those of other nations.

Nationalist exaggerate the value or importance of their homeland placing its interests over and above those of other countries