War is arguably the most important single problem of international politics.
In the 20th century alone, more than 100 million people have been killed in war. As recently as your grandparents day, most American males had served in the military and been involved in a war, and some 1.5 million Americans have been killed or wounded in combat since 1917. War has transformed the political structures of continents. Twice in this century, the map of Europe has been remade by war. Allied victory in World War II split Germany into two countries, ended Latvian, Lithuanian, and Estonian independence, and resulted in a generation of subjugation under Soviet satellite rule for the peoples of Eastern Europe.