British heavy tanks of World War I

British heavy tanks were a series of related vehicles developed by the British Army during the First World War. The Mark I was the world's first tank to enter combat. Born of the need to break the domination of trenches, barbed wire and machine guns over the battlefields of the Western Front, it was the first vehicle to be named "tank", a name chosen 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.

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, part of the Somme Offensive. With the exception of the few interim Mark II and Mark III tanks, it was followed by the largely similar Mark IV, which first saw combat in June 1917. The Mark IV was used en masse (about 460 tanks) at the Battle of Cambrai in November 1917. The Mark V, with its much improved transmission, entered service in mid-1918.

Mark I

Mark I or Mark 1 often refers to the first version of a weapon or military vehicle, and is sometimes used in a similar fashion in civilian product development. In some instances, the Arabic numeral "1" is substituted for the Roman numeral "I". "Mark", meaning "model" or "variant", can itself be abbreviated "Mk."

Military and weaponry

Mark I (detector)

The Mark I, also known as the SLAC-LBL Magnetic Detector, was a particle detector that operated at the interaction point of the SPEAR collider from 1973 to 1977. It was the first 4π detector, i.e. the first detector to uniformly cover as much of the 4π steradians (units of solid angle) around the interaction point as possible with different types of component particle detectors arranged in layers. This design proved quite successful, and the detector was used in discoveries of the J/ψ particle and tau lepton, which both resulted in Nobel prizes. This basic design philosophy continues to be used in all modern collider detectors.

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