World War I involved 32 nations from 1914 to 1919. It redrew the world map and reshaped many borders in Europe. The collapse of the Russian Empire created Poland, the Baltics, and Finland.

Stretching 440 miles from the Swiss border to the North Sea, the line of trenches, dug-outs and barbed-wire fences moved very little between 1914-1918, despite attempts on both sides to break through.

Follow the progress of the German forces as they cross the border, occupy Belgium and the Netherlands and trap the Allied forces at Dunkirk.

Esri, a spatial analytics firm based in California, has put together a animated map of California wildfires over the last century. Watch how quickly COVID-19 is spreading around the U.S. and world ...