Trenches from the Channel to Switzerland decided the Great War
After Germany invaded Luxembourg and Belgium in August 1914 and seized French industrial ground, the First Battle of the Marne halted the sweep toward Paris. From 1915 to 1917, artillery, wire, and machine guns turned the Western Front into a slaughterhouse of failed breakthroughs until 1918 restored movement.
Germany opened the front with a modified Schlieffen Plan: seven field armies in the west would swing through neutral Belgium and trap the French against their own border. Luxembourg was occupied unopposed on 2 August 1914, and Kluck's and Bülow's armies crossed into Belgium two days later. Because Britain had guaranteed Belgian neutrality in 1839, its ultimatum expired at midnight on 4 August and it entered the war. Liège held out from 5 to 16 August before heavy guns smashed its forts, and Brussels fell on 20 August. Executions of civilians and burned villages became notorious as the "Rape of Belgium."
France's Plan XVII aimed instead at Alsace–Lorraine, but its thrusts toward Mulhouse and Lorraine were thrown back with heavy losses. The Germans pressed to within 70 km of Paris before the First Battle of the Marne, 6–12 September, exploited a gap between their First and Second Armies. They withdrew behind the Aisne and dug in; mutual outflanking in the Race to the Sea then stretched trenches from the North Sea to Switzerland. The ground Germany held contained 64 percent of French pig-iron output and 40 percent of its coal industry.
After the First Battle of Ypres ended in stalemate, Erich von Falkenhayn concluded in November 1914 that arms alone could not win and urged diplomacy. Hindenburg and Ludendorff disagreed. The years 1915–1917 proved the defence stronger than the attack: Verdun cost about 700,000 casualties, the Somme more than a million, and Passchendaele 487,000. Lethal gas was first loosed in the west against French troops near Ypres, despite Hague Conventions of 1899 and 1907 banning chemical weapons.
Gas, aircraft and tanks were all tried as keys to the lock, but better tactics and exhaustion did more. After Brest-Litovsk freed eastern divisions, Germany's 1918 spring offensive used short hurricane bombardments and infiltration to advance nearly 100 km, the deepest push since 1914, before stalling. The Entente's Hundred Days Offensive then broke the German armies, leading to the Armistice of 11 November 1918 and the Treaty of Versailles in 1919.
Source: Western Front (World War I)
