From Wikipedia: The A7V was a heavy tank introduced by Germany in 1918 during World War I. One hundred chassis were ordered in early 1917, ten to be finished as fighting vehicles with armored bodies, and the remainder as Überlandwagen cargo carriers. The number to be armored was later increased to 20. They were used in action from March to October 1918, and were the only tanks produced by Germany in World War I to be used in combat.
Following the appearance of the first British tanks on the Western Front, in September 1916, the German War Ministry formed a committee, under the auspices of its Allgemeines Kriegsdepartement, Abteilung 7 Verkehrswesen ("General War Department, Section 7, Transportation"), to investigate tank development.