It was supposed to be the war to end all wars. Instead it began a cycle of violence that shaped the 20th century, brought about another World War within a generation, and whose echoes still reverberate in the 21st century. This is the story of the First World War, a bloody 4-year conflict that shaped the 20th century. By the time it ended, over 9 million people had lost their lives and more than 4 times that had been wounded. It redrew the map of Europe, and brought 4 great empires to an end. It heralded the rise of a new world, as a million American dough boys crossed the Atlantic in the defense of European liberty, while at the same time it underscored the twilight of the old world.