A year of warfare on the Western Front proved that, to be fully effective, machine guns must be used in larger units and crewed by specially trained men. To achieve this, the Machine Gun Corps was formed in October 1915 with Infantry, Cavalry and Motor branches, followed in 1916 by the Heavy Branch. A depot and training centre was established at Belton Park in Grantham, Lincolnshire, and a base depôt at Camiers in France.
The Infantry Branch was by far the largest and was formed initially by the transfer of battalion machine gun sections to the MGC, these being grouped into Brigade Machine Gun Companies, three per division. New companies were raised at Grantham. In 1917 a fourth company was added to each division. In February and March 1918, the four companies in each division were formed into a Machine Gun Battalion.
The Cavalry Branch consisted of Machine Gun Squadrons, one per cavalry brigade.
The Motor Branch, after absorbing the MMGS, formed several types of units: motor cycle batteries, light armoured motor batteries (LAMB) and light car patrols. As well as motor cycles, other vehicles used included Rolls-Royce and Ford Model T cars.
The Heavy Section was formed in March 1916, becoming the Heavy Branch in November of that year. Men of this branch crewed the first tanks in action at Flers, during the battle of the Somme in September 1916. In July 1917 the Heavy Branch separated from the MGC to become the Tank Corps, later called the Royal Tank Regiment.
The MGC saw action in all the main theatres of war, including France, Belgium, Palestine, Mesopotamia, Egypt, Salonika, East Africa and Italy. In its short history the MGC gained an enviable record for heroism as a front line fighting force. Indeed, in the latter part of the war, as tactics changed to defence in depth, it commonly served well in advance of the front line. It had a less enviable record for its casualty rate. Some 170,500 officers and men served in the MGC with 62,049 becoming casualties, including 12,498 killed, earning it the nickname 'the Suicide Club'.
At the end of hostilities the MGC was again re-organised in a smaller form as many of its soldiers returned to civilian life. However, the Corps continued to see active service in the post-war campaigns in Russia, Afghanistan, and the Northwest Frontier of India. It also served prominently in the British army which occupied parts of Germany in the period between the 1918 Armistice and the Versailles Peace Treaty. Its equipment and training made it possible for a relatively small garrison to control a large population.