The fort's construction was improved under the German Empire, which renamed it Fort Goeben after a Prussian general who had distinguished himself at the Battle of Spicheren on 6 August 1870. Immediate German construction focused on dispersing gun batteries to flanking positions and reinforcing protection for personnel and ammunition against shellfire. In 1885, new explosives led to a massive increase in the explosive power of artillery projectiles, the so-called "crise de l'obus-torpille" ("torpedo-shell crisis). This development made unprotected artillery and masonry construction entirely obsolete, as the new shells could easily destroy masonry structures. In response, concrete and earth sheltering was employed in new forts, and older forts were reinforced under the new principles. In 1885 a program of reinforcement covered some critical areas of Queuleu with concrete and provided better infantry shelters. As an early fort, Queuleu has relatively few underground passages compared to the "Moselstellung" forts of the 1890s, but does feature countermine passages extending from the front of the fort.