Known to the Germans as the Siegfried Stellung, the Hindenburg Line was a German infrastructure line of defense consisting of fortified redoubts surrounded by trenches and barbed wire. The line ran from "Arras, south to St Quentin, past La Fère, and then rejoined the front east of Soissons" (Osborn and Romanych). It was the most extensive fortification built during World War I. The name Siegfried (also the name of the poet Siegfried Sassoon) comes from a hero in ancient German literature: the main character in the poem "Nibelungenlied." The word "stellung" means position. Other names of characters from "Nibelungenlied" were also used for similar fortified positions, and the German Army often referred to these positions as Siegfried-Stellungen. The infrastructure was deemed impregnable, and indeed the Germans held out for the entire year of 1917. But in 1918, the Allied forces broke the lines of defense and on November 11th, Germany agreed to an Armistice.