The First World War in history was due to three major causes: nationalism, militarism, and imperialism. The devotion to the country, also known as nationalism, started to raise the competitive rivalries among nations. Militarism, the development of armed forces, was used to defend the growing nation and through imperialism, which is the extending of the nation through the building of colonies. The tension among the strong nations of Europe was huge; however, the assassination of Archduke Franz Ferdinand, heir of the Austrian throne, in June of 1914 was the last crucial act that led to the war. Following the assassination of their throne's heir, Austria-Hungary declared war on Serbia, who stood behind the murder of Franz Ferdinand. This activated the alliance systems and pulled one nation after another in the conflict (Danzer 580).
There were two major alliances in Europe in the time of the First World War: The Triple Entente and The Triple Alliance. The Triple Entente, later known as the Allies, consisted of France, Britain, and Russia. Germany, Austria-Hungary, and Italy made up The Triple Alliance. When Austria declared war on Serbia, Germany felt obliged by their alliance with Austria to declare war on Russia and next France, the ally of Russia. After the invasion of Belgium by the Germans, Britain declared war on Germany and supported Russia and France. Through those alliance systems more and more countries in Europe became involved in the war. Such alliances consisted of strong countries like Germany, Austria-Hungary, and the Ottoman Empire, known as the Central Powers, but also of smaller and less military developed countries like Italy. .
While Europe was already going through a war, the U.S. hadn't decided if they would join the fight. However this changed when the U.S. wanted to ensure the repaying of the Allies' debts and the threatening of U.S. shipping by the Germans. The British ship blockade prevented the trade between the U.