Once thought to be "the war to end all wars", World War I was fought from July 28, 1914 to November 11, 1918. As the conflict's main players arranged themselves into the Allied Powers (the U.K., the U.S., France, the Russian Empire, Italy, Japan, Portugal, Greece, Serbia, and Montenegro) and the Central Powers (the German Empire, the Austro-Hungarian Empire, the Ottoman Empire, and Bulgaria), Germany began an aggressive two-pronged attack. The Schlieffen Plan—so named for the strategic man behind it, German Field Marshal Alfred von Schlieffen—would see Germany invading France in the west and then rapidly confronting Russia in the east.
The Schlieffen Plan was expected to not only bring the Central Powers victory, but an exceptionally quick one. This offensive led to significant defeats of the Franco-British forces during the Battle of Charleroi and the Battle of Mons. These Allied forces began what was called The Great Retreat—a withdrawal to the River Marne. Along the way, the French Fifth Army attempted a counter-offensive at the First Battle of Guise, but their failure saw a continued retreat.
