This map is part of a series of 20 animated maps showing the history of The first World War, 1914-1918.
Pursuant to the Schlieffen plan, the German armies launched their offensive in the west, and the bulk of the troops advanced into Belgium directly across the German border or via Luxemburg.
The Belgian army was too small to stop them, but attempted to slow them down by relying on its strongholds, such as Liege or Namur.
The right flank of the German Army, composed of 68 divisions, made headway towards the west. Its strength was greatly underestimated by the French general staff, and the opposing
Franco‑British forces quickly suffered an upset. The so-called “Battle of the Frontiers” reached its climax on 22 August. Within 24 hours, the French Army had lost 30,000 men.
Retreat was inevitable. It was limited in the east, but the 4th and 5th French armies and the British Expeditionary Corps had to abandon a vast territory between Verdun and Paris.
Nevertheless, the retreat took place in an orderly manner, and after 5 September, a counter‑offensive thwarted the advance of the German troops which had reached the Marne and seemed close to victory. Forced to withdraw, they marched back towards the Aisne River where they settled into a network of trenches.
This stabilization of the front led the warring parties to try to break through in the only sector still open: northwest France. The advance movement, later known as "The Race to the Sea", ended in November 1914. From this point on, the war became entrenched from the North Sea to the Swiss border.
On the eastern front, the Russian armies stepped in sooner than the German general staff had predicted, and entered Eastern Prussia as early as 20 August. They were rapidly pushed back following the German victory at Tannenberg, but took their revenge farther south, when confronted by the Austro‑Hungarian army.
Victorious at Lemberg, now known as Lvov, the Russian troops occupied Eastern Galicia.