The combat tank made its debut on the battlefields of World War 1 (1914-1918) and proved a decisive component to Allied actions during the last year of the war. The British Army relied on its heavy lozenge-shaped steel beasts developed as mobile gun-carrying pillboxes crossing over enemy trench networks. The French, on the other hand, moved to adopt the Renault FT-17 Light Tank (detailed elsewhere on this site) and this was notable because of the design's inherent mobility and turreted main armament. At the end of the conflict, the British Army did away with its earlier "heavies" while retaining the services of the Mark V and Medium Mark C types.
The government-funded Tank Design Department missed on the post-war Medium Mark D tank which ended as a failed, ultimately abandoned design. The department was then terminated in 1923 and this allowed private concerns to present their products for possible sale to the government. Vickers interested the Army in its Medium Mark I which featured a crew of five, armor up to 25mm thick and a QF 3-pounder (47mm) main gun held in a traversing turret. Mobility was a key quality of the modern battlefield and the Medium Mark I would be powered by an Armstrong Siddeley V-8 air-cooled gasoline unit while the hull would be suspended atop a helical spring arrangement. The Mark I served the Royal Tank Regiment and several variants emerged from the basic design.
The Medium Mark II was a further continuation of the line, its development intended to succeed the line of Medium Mark C tanks still in service. The model was a largely improved form of the preceding Mark I complete with a better suspension system for cross-country travel, side armor skirts protecting the upper track sections and a revised hull superstructure. The automotive components and associated running gear were retained from the Mark I design. Armament again centered on a QF 3-pounder main gun backed by up to 4 x Hotchkiss 0.303 machine guns for anti-infantry work. Power was served through an Armstrong Siddeley V-8 gasoline engine of 90 horsepower. Road speeds could reach 15 miles per hour on ideal surfaces with ranges out to 120 miles.
The Mark II proved heavier and slower when compared to the Mark I but was nonetheless taken on by the British Army and, with the Mark I, made up the primary armored spearhead from 1925 until 1935 - laying the groundwork for a new generation of British tanks and doctrine still to come. They also contributed to various experiments witnessed throughout the late 1920s and early-to-middle 1930s, managing an existence even into the early part of World War 2 (1939-1945). The type was the first British tank to feature a sprung suspension arrangement and rotating turret for its main armament. Its initial classification was medium though the arrival of smaller, more compact forms in the period forced a revision to its official categorization.
The initial Mark II brought along with it side skirt armoring which aided in protecting the upper track regions and 100 were made to the standard. The Mark II series was also tropicalized through a 1928 model for service in the hot, dry Egyptian climate, asbestos plates serving as insulators overhead. The Mark II* then followed through 56 examples and lost its Hotchkiss machine guns in favor of a coaxially-mounted Vickers system. The Mark IIA added an armored box, this to hold a ventilator, and numbered 20 new-build vehicles arriving in 1930. The Mark II** were 44 Mark II tanks arriving in 1932 featured separate mountings for their 3-pdr cannon and 0.303 machine gun weapons and an armored box added to the rear of the turret housed a radio kit. The Mark IIA* were 20 Mark IIA models brought up to the Mark II** standard.
The Mark IIA CS was a close-support model rebuilt from previous Mark IIA tanks and replaced its standard 3-pdr gun unit with a demolition-minded 15-pdr gun for ranged support of ground forces. Heavier and more cumbersome, the model nevertheless provided a much-needed smoke-laying capability and could just as easily fire High-Explosive (HE) shells. The Mark D of 1929 was a one-off model delivered to Ireland and fitted a Sunbeam 6-cylinder gasoline engine of 170 horsepower as well as a 6-pdr main gun. This product lasted until scrapped in 1940.
Beyond these forms, the Mark II was also developed into an all-machine gun tank (the Medium II Female), a bridgecarrier (wholly experimental), a command tank (one-off example), and an experimental Self-Propelled Gun (SPG) system known as the "Birch Gun".
In 1931, the Soviet Union purchased a small batch of fifteen Mark IIs and these were nicknamed "English Workman". The existed primarily as trainers and were still on hand during the Soviet invasion of Finland (the "Winter War" of 1939-1940). The Finns manage capture of as many as six engine-less examples in the fall of 1941 (during the "Continuation War" of 1941-1944).
Officially identified as obsolete by the time of World War 2, the Mark II was no less still available in some number with British forces and retained as driver trainers. Some were reactivated as frontline tanks following the losses in France and remained on hand until the threat of invasion of the British homeland subsided. Numbers were delivered to Allied forces in Egypt to shore up losses and increase strength there and some of these were arranged as fixed defensive battlefield pieces at Tobruk and Mersa Matruh.
Mark IIs remained in notable active service until 1939 by which point they were officially succeeded by the Cruiser Mk I (A9) which appeared from 1938 onward and saw 125 of their kind produced. The Cruiser Mk II was a heavier model based on this original design. Cruisers made up one-half of the new British Army fighting doctrine of cruiser / infantry tanks intended to overwhelm enemy positions. The concept was abandoned following World War 2 with the arrival of the Main Battle Tank (MBT).