The first tank used in battle on Sept. 15, 1916, was the British Mark I. The word “tank” was applied to these armored landships even before they entered battle, to keep their nature and use secret.
The type was developed in 1915 to break the stalemate of trench warfare. The Mark I was a development of Little Willie, the experimental tank built for the Landship Committee by Lieutenant Walter Wilson of the Royal Naval Air Service and William Tritton of William Foster Co., between July and September 1915. It was designed by Wilson in response to problems with tracks and trench-crossing ability discovered during the development of Little Willie.
History of tanks 