Arranged Marraige: Africa
A cause of World War I not often discussed is the intense competition to rape Africa. A simple google search of “Scramble for Africa” would return you with plenty results citing the time period of the scramble as 1881-1914. There is no coincidence that World War I started in 1914. It is easily proving that tensions at during that time period were high among the European nations that wanted to colonize Africa for themselves. The Berlin conference was an effort put forth by several of these countries in order to try and ward off a war over Africa. So Action was taking similiar to when a prince chooses a princess to bring to countries together. The princess has no choice in the matter and neither did Africa. At the Berlin Conference the countries drew lines on a map of Africa and thus determined who was allowed to satomize which seection of Africa. France got most of West Africa, Belgum the Congo, Britian East and South Africa, Portugal 2 Colonies in South Africa, and Germany a small colony in each region. I Dont think it is a coincidence that Germany lost all four of its colonies after it lost WWI.
The picture on the left indicates variety causes of WWI. Arms Force plays a important role in WWI. Since the alliances was formed after 1871, it led to an armaments race among the powers. The tension was being serious between when Germany passed Navy Laws in 1900. 
The main reason for the American entry into World War I was the German use of submarine warfare (1917), violating the United State right to freedom of the seas. German was suffering from near- starvation due to a lack of supplies and food. German military leaders feared they would lose the war unless they could defeat Britain and France quickly. They therefore took a risk by announcing they would they would sink any ship in the blockaded areas. This was a clear violation of the American principle of freedom of the seas that neutral parties have the right to ship non-war goods to nations at war. When German followed up its threat by ordering its submarines to sink three unarmed American merchant vessels, Wilson asked congress for a declaration of war against German.