The Western Front of World War I was opened in 1914 after the army of the German Empire invaded Belgium and Luxembourg, thereby gaining military control of important industrial areas in France. The advance of the Empire underwent a dramatic turn after the first Battle of the Marne, where the alliance between France and the United Kingdom won. Both sides - Allies and Central Powers - settled in a sinuous line of fortified trenches, stretching from the North Sea to the Swiss border with France. That line remained static for most of the war.
