Eric Morris, Tanks, Modern Military Series, Octopus Books 1975
British tanks were first deployed in September in 1916 at the Battle of the Somme. The German reply didn't come till 1918 and was in the form of this giant, the A7V Land Fortress. Twenty were constructed before wars end. They were not considered a success, weighing 30 tons with a 17 man crew and being top heavy and underpowered. The armour was sufficient to repel only rifle and machine gun fire.