40 maps that explain World War I

One hundred years ago today, on August 4, 1914, German troops began pouring over the border into Belgium, starting the first major battle of World War I. The Great War killed 10 million people, redrew the map of Europe, and marked the rise of the United States as a global power. Here are 40 maps that explain the conflict — why it started, how the Allies won, and why the world has never been the same.

by Zack Beauchamp, Timothy B. Lee and Matthew Yglesias on August 4, 2014