High Quality Content by WIKIPEDIA articles! The British Mark I was a tracked vehicle developed by the British Army during the First World War, and the world`s first combat tank. The Mark I entered service in August 1916, and was first used in action on the morning of 15 September 1916 during the Battle of Flers-Courcelette, of the Somme Offensive. Born of the need to break the domination of trenches and machine guns over the battlefields of the Western Front, it was the first vehicle to be named "tank", as an expedient to maintain secrecy and to disguise its true purpose. It was developed to be able to cross trenches, resist small-arms fire, travel over difficult terrain, carry supplies, and to capture fortified enemy positions. It is regarded as successful in many respects, but suffered from many problems owing to its primitive nature.