Causes of WW1

Nationalism is a main reason of WWI because Europe thought that they were better than everyone else and every other country. So countries like Elba, Britain, Austria, Prussia and Russia went against Europe. 

Militarism is a main reason of WWI also because all the countries in the hostile camps were building large armies. So then a large class of powerful and professional military officers conquered the civil authorities. However these armies made plans for mobilization. But these secret battle plans nourished greater fear and hatred.

Assassination of Franz Ferdinand was another main reason to the WWI because since Ferdinand was assassinated in Austria, countries like Russia tried to put the blame on Austria. And then countries after countries started declaring war on each other. Then leading to one big world with two alliances.