War does not start in a day. The immediate cause of World War 1 (WW1) was the assassination of Archduke Franz Ferdinand, but there were three more underlying tensions that were imperialism, militarism, and nationalism. One of the most influential ideas in Europe during the early 1900's was imperialism.
Imperialism is the policy of extending a nation's authority by territorial acquisition or by the establishment of economic and political hegemony over other nations (The American Heritage® Dictionary of the English Language). Germany saw that other European powers were acquiring colonies around the world, and now that there were only a small amount of useless colonies, Germany had to fight the other Europeans for land. WW1 just gave Germany an excuse for battling other countries. Due to the imperialist ideas in Europe, tension was created between the European powers as Germany realized it need colonies. Imperialism was a very important underlying cause of WW1, but there were also other cause, another one of them was militarism.
Militarism was the build up of a nations arms and military technology. This tension was started by Germany, which started to build up its army and navy. This started an arms race between the European nations. Even though an arms race was a reason to build and develop an army, there was another. Countries thought that the larger the army, the less people would think of attacking them. They thought it would produce peace. Militarism is an idea that is still practiced to this day; hopefully it will not end up in world war as the European nations did. Imperialism and militarism are both very affective underlying causes, but the tension that eventually "pulled the trigger" to war was nationalism.
Nationalism is one's strong feelings/emotions or loyalty to its country. All the people in Europe felt this loyalty, but one place that might have felt it the most was in Serbia. The Serbs and the Bosnians wanted to...