Eight Mörsers were loaned to the German Army and they were first fired in action on the Western Front at the start of World War I. They were used in concert with the Krupp 42 cm howitzer ("Big Bertha") to destroy the rings of Belgian fortresses around Liege (Battle of Liège), Namur (Fortified Position of Namur) and Antwerp (Forts Koningshooikt, Kessel and Broechem). While the weapon was used on the Eastern, Italian and Serbian fronts until the end of the war, it was only used on the Western front at the beginning of the war.