One of the major causes of World War I was imperialism. The industrialized nations felt that they had to have colonies. To be a great power and be respected you had to have colonies. They were also needed as a source for raw materials and as a market to sell their manufactured products. Italy was united into one nation only around 1860 as Germany was united into one nation in 1870. By then the best lands for raw materials were already taken by the British, French, Belgium and Dutch. The Germans and Italians felt left out in the cold. The Germans especially were jealous of the British Empire, that "the Sun never set on". They wanted to exploit underdeveloped lands. Also Austria-Hingary desired to control Bosnia, which would give it a shoreline for its navy. France wanted revenge against Germany for its defeat in the earlier Franco-Prussian War. France wanted to regain Alsace-Lorraine from Germany. Japan joined the Allied cause just so she could acquire some islands in the Pacific that Germany controlled. So you see imperialism was the major cause of World War I. I hope that this has been a help to you.