The war between austria and serbia should have been a small regional conflict in one corner of europe. how did nationalism, militarism, and the new imperialism contribute to its expansion into a global conflict?

The war between Serbia and Austria was a nationalist in terms that both wanted to gain greater land for their country. Serbia wanted to have Bosnia and Herzegovina which were both under Austria. It declared war after Serbia refused to surrender the group who planned the assassination of Archduke Ferdinand. 

This kind of regional wars that involved territorial expansion pushed to World War I. Countries searched for allies and cooperated to have a greater military strength and support to defeat other countries they wanted to have.