In August 1914, German forces under the command of General Otto von Emmich appeared before Liège and summoned it to surrender. On Gen. Leman's refusal, the fortress was attacked, and the Battle of Liège began. Gen. von Emmich's forces were initially unable to break through his fortifications: only after they used very heavy artillery (Big Bertha and other heavy guns, brought from Germany and Skoda works), against the forts did they succeed in knocking them out. Leman was knocked unconscious by the bombardment, and was rescued by the Germans from under the debris of Fort Loncin. He was held as a prisoner of war in Germany until 1917, when he was repatriated to Switzerland due to ill health. As a token of respect, he was allowed to retain his sword. Leman insisted that the report of his capture mentioned that he did not surrender, but was captured unconscious.