Known as the Great War, the War to End All Wars or even the Chemist's War, it was the most devastating conflict the world had seen up to that time. Europe's great powers were engaged in a toxic combination of imperialism, nationalism, sabre-rattling, and botched diplomacy. The spark to to set it off came when a Serbian nationalist assassinated the heir to the Austria-Hungarian Empire in Sarejvo in June 1914. By the end of July war was declared, between the Central Powers (Germany, Austria-Hungary, Ottoman Empire) and the Allied Powers (Britain, France, Belgium, Russia, Italy, and eventually, the United States). It's estimated 10 million men were killed, and another 20 million wounded--a generation lost to the slaughter.