A Game Changer During WWI, much of Western Europe was reduced to a massive battlefield criss-crossed by a seemingly unending network of trenches. The original British Mk.I tank was developed to break the deadlock; the Mk.IV was a later model based on many of the same design principle, and of which around 1,000 were produced starting in March 1917. A """"Male"""" variant was developed to smash through enemy lines and in addition to machine guns it utilized large 6-pounder guns, in contrast to the separate Female variant equipped with only machine guns for armament. The Mk.IV saw a variety of action, including a mass deployment of around 400 at the Battle of Cambrai in November 1917, additionally prevailing in the world's first tank on tank battle with the German A7V in April 1918.