.:Military Alliances:. We were alliances with britian and when germany slowly started to take over all of europe. The U.S did not want no barrier between them and the germany forces so they wanted to keep some countrys inbewteen them and the fighting and thought it was extremely important to keep britian free of germany.
.:Imperialism:. Every country wants new land to control for profit and more land for military advantages. Then germany wanted to take over all of europe for military advantages. Also we did not want them to have that land so we joined with several forces(treatys).
.:Militarism:. In the 1900 at the beging every country thought it was important to spend a large cunk of there proftit buffing up there military. With all these improvements it made countrys nervous of each other with all these military power just laying around.
.:Nationalism:. Because all these small independent states wanted to become there own country. Some did get there wish and became free but many was left unfinished and it built tension up in europe.
.:assassination of Archduke Franz Ferdinand:. When he was assasinated it caused a whole lot of nations to get involed because Austria-Hungary attacked Serbia in retaliation for the assassination. So then the Russians got involed in to help the serbia. That then led to germany jumping in to help Austria-Hungary.