Answer:
The major cause of World War I was that all of the little alliances in Europe that all of its major powers were making finally caught up to them and led them to great conflicts. The two major alliances were the Central Powers (Germany, Austria-Hunary, and Italy) and the Triple Entente (United Kingdom, France, and Russia), which surprisingly enough holds the countries on either side of World War I; Germany, Austria-Hungary, and Italy VS. United Kingdom, France, and Russia.