Here are search results in Google for world war I causes:
There's LOTS of information in here.
here is my answer
What caused World War One and was it inevitable ?
I'am going to give out my opinion and explain briefly what caused the war.
Years before 1914 , tension bulit up between the European countries. I agree that the assassination had lead the war but tension was the main reason of World War one.
Britain , had the largest navy at that time , meanwhile Germany had begun building up her own empire which made Britain feel suspicious and worried. The two countries competed on who had the best navy. This is also called " militarism". Also, tension had built up between Gremany and France. Many years ago , in 1871, France was defeated by Germany who won a legendary victory. France was keen for revenge on Germany . Another reason for World War One was that Europe was divided into two Alliances,The Triple Entente and The Triple Alliance.
As empires grew more and more and tension builds up with alliances threatening each other, it was assumed that everyone was ready for a war. I agree that the war was inevitable because there was no doubt and it felt like as if there was only one thing to lead those powerful countries to war. This was the assasination of the Archduke of Austria where he was shot by a Serbian terrorist. Austria wanted a sign to declare war on Serbia and she did. All of this was like a linked chain that finally had a reason to happen. It finally had become by the powerful countries of Europe declaring war on each other in 1914.