During WW2, the German armed forces were by far the greatest user of half-track vehicles. Such vehicles were used in the Wehrmacht, Luftwaffe and Waffen-SS, where they served as personnel carriers, tractors, combat engineering vehicles, as well as self-propelled carriages for antiaircraft guns. Sd.Kfz. 8 Schwerer Zugkraftwagen 12t - (heavy half-track vehicle 12 tons) was a German half-track that saw widespread use in World War II. Its main role wa as a prime mover for heavy towed guns such as the 21 cm Mörser 18, the 15 cm Kanone 18, and the 10.5 cm FlaK 38. Approximately 4,000 were produced between 1934 and 1945. It was used in every campaign fought by the Germans in World War II. Sd.Kfz. 9 Schwerer Zugkraftwagen 18t - (heavy 18 ton half-track vehicle) was the Germans' heaviest half-track vehicle of any type built during the war years. Its main roles were as a prime mover for very heavy towed guns such as the 24 cm Kanone 3, and as a tank recovery vehicle. Approximately 2,700 were produced between 1938 and 1944.