1. The original mortars were quite large and needed four small wagons to transport them-this made them useless when the war became more mobile in late 1918. They also became less useful when the Germans made their frontlines less heavily defended in 1917. Trench Mortar It was a French design and was introduced in 1915. • Given the problems created by its size after the War the mortar was developed to be more mobile and smaller but with the same punch. • Now they are handheld and can fire incendiary and tracer rounds. The 240mm mortar could fire 2400 yards but was more effective over sorter distances. The Trench Mortar was developed for destroying enemy strong points on the frontline, especially when they were too strong to be destroyed by small arms fire but too small to be effectively targeted by field guns behind the frontline. These targets included bunkers and covered shelters. Original sketches, this is the US sketch but it is identical to the French design “the use for which it is primarily adapted is in the bombardment of strongly protected targets—dwellings, covered shelters, command posts, entrances to galleries, etc—or in the destruction of sectors of trenches, salients and the like” Quote from US army handbook Trench Mortar in use Modern day mortar