An analysis of the dominant international theories practiced during the 19th and 20th centuries has shown the trend away from realism, where power politics for Land control dominated foreign policies. , to liberalism, with international economic interdependence and the development of international non-governmental agencies. International politics ceased to be an all-for-one attitude as modern technology brought global economies and a social consciousness that extended to the entire planet. Empires and imperialism marked the 19th century. States generally managed diplomacy through their ambassadors. Career diplomats became familiar with each other and the countries from which they came and in which they worked during the 19th century. The way rulers treated diplomats was the same as in the 17th century. American expansion began in earnest with the cry of “Manifest Destiny.” United States economic imperialism brought additional land to the country through the war with Mexico, treaties with Britain, Russia, and the Hawaiian kings. European imperialism included, among other expansionist programs, the colonization of Africa. European leaders sent company agents who scoured the interior to find other resources that Africans may not have known existed or had value in European eyes. Colonization by British companies also occurred in India by the East India Company, which was a political and economic imperialism similar to that of East Africa in Egypt and the Kimberley diamond mines in South Africa. South. Meanwhile, dominant European states formed alliances based on ideological principles. , like the Holy Alliance of Russia, Prussia and Austria. These states joined because of their common relationship...... middle of paper ......Francis e-Library.McLeod, John. The History of India. Westport: Greenwood Press, 2002. Pletcher, David M. The Diplomacy of Involvement: American Economic Expansion Across the Pacific, 1784-1900. Columbia: University of Missouri Press, 2001. United Nations. Charter of the United Nations. October 24, 1945. 1 UNTS XVI. http://www.un.org/en/documents/charter/chapter1.shtml (accessed December 4, 2011). Viola, Lora Anne. “The reinvention of diplomacy: are international negotiations becoming more democratic? WZB-Mitteilungen, Heft 121 (September 2008). http://bibliothek.wzb.eu/artikel/2008/f-14290.pdf (accessed December 3, 2011). Wilson, Woodrow. “January 8, 1918: President Woodrow Wilson's Fourteen Points. » The Avalon Project, Lillian Goldman Law Library (2008). http://avalon.law.yale.edu/20th_century/wilson14.asp (accessed December 4, 2011).