The Germans studied the Siege of Port Arthur, where heavy artillery had been unable to destroy defensive structures like barbed wire and bunkers. The German Military Ingenieurkomitee ("Engineer committee") began working with Rheinmetall to study the problem in 1907. The solution they developed was short-barreled rifled muzzle-loading mortar, built in three sizes. The largest of these was introduced first, in 1910 as the 25 cm schwerer Minenwerfer (abbreviated "sMW"; English: "25 cm heavy mine launcher"). Despite weighing only 955 kg (2,193 pounds) it had the same effect on targets as the 28 cm and 30.5 cm mortars, which weighed ten times as much. At the outbreak of the First World War 44 had been delivered. They were used successfully in Belgium at Liege and Namur, and against the French f