CHAPTER: America at War: World War I in World War I Era[All sections required.] Economic and human costs of World War I and political consequencesWorld War I killed more people (more than 9 million soldiers, sailors, and flyers and more than 5million civilians), involved more countries (28 nations), and cost more money ($186 billion in direct costs and another $151 billion in indirect costs), than any previous war in history. It was the first war to use airplanes, tanks, long-range artillery, submarines, and poison gas. It left at least 7 million men permanently disabled. Four years of war killed a million troops from the British Empire; 1.5 million troops from the Hapsburg Empire; 1.7 million French troops; 1.7 million Russians; and 2 million German troops. The war left a legacy of bitterness that contributed to World War II some 21 years later.How the war beganOn June 28, 1914, a car carrying Archduke Franz Ferdinand, heir to the imperial Hapsburg throne, made a wrong turn. As the car came to a halt and tried to turn around, a nervous teenager approached from a coffee house, pulled out a revolver, and shot twice. Within an hour, the Archduke and his wife were dead.Gavrilo Princip, the 19-year-old assassin, was a Bosnian nationalist who opposed the dominationof the Balkans by the Austro-Hungarian Empire. He had received his weapon from a secret society known as the "Black Hand," which was clandestinely controlled by the government of Serbia. Princip died of mistreatment in an Austrian prison in 1918.The assassination provoked outrage in Austria-Hungary. The dual monarchy wanted to punish Serbia for the assassination and to intimidate other minority groups whose struggles for independence threatened the empire's stability. The assassination of the archduke triggered a series of events that would lead, five weeks later, to the outbreak of World War I. When the conflict was over, between 9 and 15 million people had been killed, four powerful European empires had been overthrown, and the seeds of World War II and the Cold War had been planted.A complicated system of military alliances transformed the Balkan crisis into a full-scale European war. Recognizing that any action it took against Serbia would create an international incident, Austria asked for Germany's diplomatic and military support. Meanwhile, Russia, fearful of Austrian and German expansion into the Balkans, strongly supported the Serbs and began to mobilize its army.This move made Germany's leadership fear encirclement by Russia and France. Germany sent anultimatum to France asking it to declare its neutrality in the event of a conflict between Russia and Germany. The French refused. They were obligated by treaty to support Russia and were stillbitter over their defeat by Prussia in 1871. When Russia failed to demobilize its forces, the German Kaiser agreed to war.