Third Republic of France in the context of "Territoire de Belfort"

The Western Front was one of the main theatres of war during World War I. Following the outbreak of war in August 1914, the German Army opened the Western Front by invading Luxembourg and Belgium, then gaining military control of important industrial regions in France. The German advance was halted with the Battle of the Marne. Following the Race to the Sea, both sides dug in along a meandering line of fortified trenches, stretching from the North Sea to the Swiss frontier with France, the position of which changed little except during early 1917 and again in 1918.

Between 1915 and 1917 there were several offensives along this front. The attacks employed massive artillery bombardments and massed infantry advances. Entrenchments, machine gun emplacements, barbed wire, and artillery repeatedly inflicted severe casualties during attacks and counter-attacks and no significant advances were made. Among the most costly of these offensives were the Battle of Verdun, in 1916, with a combined 700,000 casualties, the Battle of the Somme, also in 1916, with over a million casualties, and the Battle of Passchendaele, in 1917, with 487,000 casualties.

Joseph Jacques Césaire Joffre OM, GCB (French: [ʒozɛf ʒɔfʁ]; 12 January 1852 – 3 January 1931) was a French general who served as Commander-in-Chief of French forces on the Western Front from the start of World War I until the end of 1916. He is best known for regrouping the retreating allied armies to defeat the Germans at the strategically decisive First Battle of the Marne in September 1914.

His political position waned after unsuccessful offensives in 1915, the German attack on Verdun in 1916, and the disappointing results of the Anglo-French offensive on the Somme in 1916. At the end of 1916 he was promoted to Marshal of France, the first such elevation under the Third Republic, and moved to an advisory role, from which he quickly resigned. Later in the war he led an important mission to the United States.