The Krupp 13.5 cm (5.31 in) FK 1909 was introduced into German service in 1909, however by 1914 only 16 had been built. Production was accelerated when war began, but in 1915 it was withdrawn from service and replaced with guns capable of higher angles of elevation and longer range. Later in the war the FK 1909 was brought back into service due to attrition and shortages. A sprung axle was fitted in order to improve its mobility and allowed the FK 109 to be towed by artillery tractors instead of horse teams. By the end of the war there were 200 in service, however the FK 1909 was not considered one of Krupp's better guns, due to its large size and small shell size.