a7v (tank)
The A7V was the only German tank to see combat in World War I. It is notable for its boxy shape, with every side featuring a weapons emplacement, being armed with one canon and six machine guns. It had a very high crew requirement at 18, and while it had good road speed it's cross-country capability was poor. Only 20 vehicles were produced, and the tank had little overall impact on the war.
The A7V first saw action on 21 March 1918 at the St. Quentin Canal, and also participated in the first tank versus tank combat against British Mark IVs at the Second Battle of Villers-Bretonneux.