Mark IV

Overview and variants

The Tank, Mark IV was the principal British heavy-tank production development of 1917. It retained the Mark I's rhomboid form while introducing changes to protection, fuel arrangements, armament, and handling. It was an improved production vehicle rather than a completely new mechanical design. ^{1, 2, 3, 4, 5, 7, 9, 16}

Male, Female, and Supply vehicles were the principal production categories. Composite or Hermaphrodite weapon arrangements and the Tadpole extension reflected specialized or experimental adaptations. German use of captured tanks was a separate service history, not a new manufacturing program. ^{1, 2, 3, 4, 5, 7, 9, 16}

One production breakdown totals 1,220 tanks: 420 Male, 595 Female, and 205 Supply vehicles. A museum collection record instead gives 1,222. The cited evidence does not reconcile the totals or identify two additional experimental vehicles that would explain the difference. ^{1, 2, 3, 4, 5, 7, 9, 16}

Development and changes from earlier Marks

The Mark IV program followed British tank experience in 1916 and the demand for a larger force. The cited chronology places the start of production in March 1917, arrival in France during the spring, and entry into service in May. Development during 1916 preceded its combat introduction. ^{1, 3, 4, 5, 7, 8, 9}

Changes addressed practical vulnerabilities and handling difficulties. Protective plate was improved, fuel was moved to a protected rear arrangement, and shorter 6-pounder guns on the Male reduced problems associated with the earlier long weapons. Revised sponsons eased rail transport and movement through restricted spaces. ^{1, 3, 4, 5, 7, 8, 9}

The Mark IV retained an earlier powertrain and control arrangement that required several crew members to cooperate in maneuvering. It did not have the later Mark V's engine and steering system. ^{1, 3, 4, 5, 7, 8, 9}

Hull, weapons, crew, and protection

The Mark IV had no rotating turret. Male tanks carried their principal weapons in side sponsons, while Female tanks emphasized machine-gun fire. The hull, track frames, and weapon positions determined the fields of fire and the work of an eight-man crew. The available weapon arcs differed markedly from those of a turreted tank. ^{1, 2, 3, 4, 5, 7, 8, 9, 13, 14}

Sources and preserved examples show differing machine-gun counts and installations. These describe individual configurations rather than one uniform weapon fit throughout the family's service life. ^{1, 2, 3, 4, 5, 7, 8, 9, 13, 14}

Published armor figures include approximately twelve and fourteen millimeters in different descriptions. The cited evidence does not establish whether differences in plate location, measurement, vehicle condition, or reporting conventions account for the discrepancy. ^{1, 2, 3, 4, 5, 7, 8, 9, 13, 14}

Conditions inside remained cramped, hot, and noisy, with restricted vision. Driving, changing direction, and serving the weapons demanded close cooperation. Exact ammunition stowage, sight installations, and changes to interior arrangements remain uncertain. ^{1, 2, 3, 4, 5, 7, 8, 9, 13, 14}

Power, tracks, and support equipment

The family is associated with a Daimler-Knight petrol engine of approximately 105 horsepower and a quoted maximum road speed of around 3.7 miles per hour. Battlefield movement was often much slower. Wire, damaged trenches, soft ground, and the recovery of ditched vehicles could dominate the time required for a short operation. ^{1, 2, 3, 4, 5, 7, 8, 13}

The surrounding tracks gave the tank its characteristic trench-crossing form but did not prevent bogging or mechanical failure. Grousers, unditching equipment, and other aids formed part of its operating equipment. ^{1, 2, 3, 4, 5, 7, 8, 13}

Rail transport was essential to moving tanks to the front. Revised sponsons helped address width restrictions, while factories and workshops handled the heavy assemblies. Supply vehicles carried material instead of performing the armed roles of Male and Female tanks. ^{1, 2, 3, 4, 5, 7, 8, 13}

The Tadpole extension was an experiment intended to improve obstacle crossing, not a normal feature of Mark IV service tanks. Its production and operational history are not established to the same extent as those of the basic vehicle. Mixed-armament and other specialized configurations also had distinct histories. ^{1, 2, 3, 4, 5, 7, 8, 13}

Manufacture and production accounting

Large-scale production drew on Metropolitan, Fosters, Armstrong Whitworth, Coventry Ordnance Works, Mirrlees, and Beardmore. Some firms assembled complete vehicles; other work involved hulls and major subassemblies. Component manufacture, final assembly, and army acceptance were different stages of the production process. ^{1, 3}

The surviving industrial accounts do not resolve the conflicting overall production totals. ^{1, 3}

Captured tanks repaired for German service and later British conversions were not licensed new production. A complete monthly output curve and firmly established unit-cost history are not available in the cited sources. ^{1, 3}

Combat, operators, and later roles

The British Army was the principal operator. German forces repaired and used captured Mark IVs in Beutepanzer service. Counts of available, rebuilt, and committed captured tanks describe different categories from British factory output. Transfers for war-loan demonstrations, preservation, and display were not frontline foreign service. ^{1, 2, 4, 5, 6, 7, 8, 9, 11, 16, 17, 18, 19}

The combat history includes Messines, the Ypres fighting, Cambrai, and operations into 1918. Ground conditions and cooperation with infantry, artillery, engineers, and supply services shaped the results. ^{1, 2, 4, 5, 6, 7, 8, 9, 11, 16, 17, 18, 19}

At Cambrai in November 1917, initial British gains were followed by a German counterattack and limits on the operation's lasting success. The initial tactical achievement did not become a sustained strategic breakthrough secured by tanks alone. ^{1, 2, 4, 5, 6, 7, 8, 9, 11, 16, 17, 18, 19}

On 24 April 1918, Mark IVs encountered German A7Vs near Villers-Bretonneux. The differing armaments of Male and Female tanks were important to the engagement. ^{1, 2, 4, 5, 6, 7, 8, 9, 11, 16, 17, 18, 19}

As improved tanks arrived, Mark IVs continued in supply and other adapted roles. Some photographs show unarmed vehicles performing possible airfield or transport duties, but they do not establish a separately manufactured tug variant. ^{1, 2, 4, 5, 6, 7, 8, 9, 11, 16, 17, 18, 19}

Preserved vehicles and gallery interpretation

Preserved examples, including Lodestar III and the museum Female illustrated here, allow examination of hull construction and armament arrangements. Each has an individual service, preservation, and restoration history rather than representing an untouched standard wartime configuration. ^{1, 2, 4, 7, 8, 11, 12, 13, 14, 15, 17, 19}

The photographs also show damaged wartime tanks, a tank named Henry, and supply vehicles. The interpretation of one photographed vehicle as an aircraft tug remains uncertain. ^{1, 2, 4, 7, 8, 11, 12, 13, 14, 15, 17, 19}

Photographs and image credits

Background reading and references. Each photograph has its own source and credit.

British Mark IV tank Henry with a Ford Model T at Bapaume in 1918; Australian War Memorial P01322.010.Australian War Memorial, P01322.010 / public domain.Image source

Preserved Mark IV Male Lodestar III at the Royal Museum of the Armed Forces and Military History in Brussels, photographed in 2016; museum condition is not treated as wartime configuration.Alan Wilson / CC BY-SA 2.0.Image source·CC BY-SA 2.0

Preserved or restored British Mark IV Female photographed in 2012; used for visible Female configuration only, not as a combat photograph.Marc Palumbo / CC BY 2.0.Image source·CC BY 2.0

Mark IV Supply Tank moving toward the line near Villers-Bretonneux in August 1918; Australian War Memorial C04889.Australian Official Photographer / Australian War Memorial, C04889 / public domain.Image source

Unarmed Mark IV Supply Tank no. 402 at an unidentified air base in 1918; the Australian War Memorial describes aircraft-tug use as probable.Australian War Memorial, P04460.016 / public domain.Image source

Mark IV Supply Tank at a tank park near Villers-Bretonneux on 28 June 1919; the postwar date remains explicit.Unknown Australian Official Photographer / Australian War Memorial, E05424 / public domain.Image source

Sources and further reading