Though there are many causes for different countries to have entered World War I, some of the main reasons were heightened nationalism, economic interest through colonial rivalry, and a balance of power in Europe. Key players were the Central powers consisting of Germany, Italy, and Austria-Hungary; the Allies, a few of which were France, Great Britain and Russia.
Europe was in the grip of nationalism in 1914. It was brought about by the aristocracy as a way to channel public energy toward national ventures and away from demands for increased democratization. People of the same ethnic backgrounds, language and ideals came to realize they had the right to self-determination, which could and did lead the formation of separate sovereignties. New states, especially in the Balkans and other ethnic groups, wanted national identity. It can be argued that the result of increased nationalism can be linked to Imperialism.
To maintain world prestige, during the late 1800's and early 1900's, European nations made nearly all of Africa and much of Asia into colonies. The race for colonies was fueled by Europe's increasing industrialization. Colonies supplied European nations with raw materials for factories, markets for manufactured goods, and opportunities for investment. However, the competition for colonies strained relations among European countries. Incidents between rival powers flared up almost every year, and almost led to war. Some of the conflicts included Russia and Great Britain in the Middle East; Britain and France in the Far East; and Britain and Germany in Africa. They made an attempt to ensure self-preservation and security by developing alliances with other countries and amongst themselves.
Political and military alliances gave European powers a sense of security before World War I. A country hoped to discourage an attack from its enemies by entering into a military agreement with one or more other countries. In case of an attack, these...