Who and What instigated World War 1?

                              

The Archduke and his Wife the Day of the Assassination

World War 1 started out with a conflict between Serbia and Austria-Hungary. In Serbia there was a group of Serbian nationalists who called themselves "The Black Hand", they wanted Austria-Hungary out of Bosnia so they planned on killing the Archduke, Franz Ferdinand On June 28 1914, Gavrillo Princip, a member from "The Black Hand" assassinated the Archduke and his wife. This I think is what instigated WW1.

I think that the assassination was what instigated WW1 but I think Austria-Hungary was the reason it started. The reason I think this is, is because Austria-Hungary had been looking for an reason to wage a “preventative war” against Serbia so they can weaken or destroy Serbia and to take back territory which Serbia had captured during the Balkan Wars, if the "Black Hand" had not assassinated the Archduke they would of had no reason to wage war on Serbia and WW1 wouldn't have started, Another reason that I think that this incident  instigated the war is the assassination caused Austria-Hungary to send a letter to Serbia (July Ultimatum) stating various demands and if Serbia didn't accept basically there would be a war. Serbia partially accepted but rejected some of the demands. This gave Austria-Hungary a reason to go to war. The next day, Austria- Hungary had declared war on Serbia starting WW1. 

Even though the assassination was done by a Serbian Nationalist I think that Austria-Hungary instigated the war because Serbia was relatively hostile to the death of the Archduke and said it had nothing to do with the government of Serbia and even though they responded quite well to the Ultimatum Austria-Hungary didn't care and declared war, but this little war over some land quickly escalated in to a long war because each country was joined by other countries all over the globe because there were a variety of existing treaties dating back as much as 75 years before the war started.