The 25 cm schwerer Minenwerfer (German name for "mine launcher"), often abbreviated as 25 cm sMW, was a heavy trench mortar developed for use by engineer troops during the Russo-Japanese War of 1905. This class of weapon was for destroying bunkers and fortifications that were otherwise immune to normal artillery. Heavy mortars were used by engineers to clear obstacles such as bunkers and barbed wire,and other obstacles that longer range artillery could not target.