How did european nationalism contribute to the outbreak of world war i?

Nationalism led to arrogance among the citizens of various nations by promoting a sense that people of a particular country were superior to those of other nations and by giving people the impression that they could win any war thanks to their togetherness. 

i confess that there are several parts of this constitution which i do not at present approve, but i am not sure i shall never approve them: for having lived long, i have experienced many instances of being obliged by better information or fuller consideration, to change opinions even on important subjects, which i once thought right, but found to be otherwise. it is therefore that the older i grow, the more apt i am to doubt my own judgment, and to pay more respect to the judgment of others.

the following best describes postwar era writers in their works:

many writers,authors,novelists,poets concentrated more on social art and social writing and stayed away from political writings.