World war one was a military conflict from 1914-1918. it started out as a European war between Austria-Hungary and Serbia, but soon many nations were involved, an eventually became a global war. The associated powers opposed the nations that were in the central powers.
The war between Austria-Hungary and Serbia was the result of the Austria Archduke and his wife being assonated. I believe the Serbs feared the archduke would continue to persecute Serbs living in the Austria-Hungary Empire. Russia decided to mobilize against Austria. Germany warned Russia that this action would