When the first tanks were produced in 1916, they were manned by members of the Machine Gun Corps, formed into six companies which were collectively known as the Heavy Branch.

The very first battle involving tanks took place on the Somme. About thirty British Mark 1 tanks attacked German positions between the villages of Flers and Courcelette, on Friday 15 September 1916. The arrival of the tanks on the battlefield signalled the end of trench warfare, which had suffocated both sides in the 1914-18 conflict.

During this action the Press seized on a report from an aircraft crew, which said that "a tank is walking down the main street of Flers with the British Army cheering behind it." This was "D" Company, later the 4th Royal Tank Regiment. These companies were expanded to form battalions and were renamed the Tank Corps in 1917.

The first battle between two opposing tanks took place near the village of Cachy on 24 April 1918. The German A7V tank Nixe (Lt Biltz), engaged three British Mark IV tanks, and damaged two, but was knocked out by the third, commanded by 2/Lt Frank Mitchell.

By December 1918 there were 26 battalions, and as well as serving in France, a detachment from the Corps had served under Allenby at Gaza, Palestine in 1917. The Corps saw almost continuous action, winning four VC's.