Medium Mark B

Overview and classification

The Medium Mark B was a British attempt to combine the obstacle-crossing characteristics of the heavy rhomboidal tanks with a smaller machine-gun vehicle intended for a different battlefield role. It emerged late in the First World War and did not reach combat before the Armistice. Its limited postwar service and the rival Medium Mark C program are important to understanding why the design did not become a large enduring fleet. Sources

Although the name “Whippet” appears in discussion of British medium tanks, the Medium Mark B is distinct from the Medium Mark A. It had a distinctive fixed fighting compartment, a single engine and its own production history. The account also distinguishes the built machine-gun configuration from a proposed gun-armed Male that was not put into production. Sources

The working production account gives 102 built and forty-five accepted, leaving the condition and disposition of the balance as a question rather than an excuse to choose whichever number is larger. Orders, completed vehicles, accepted vehicles and vehicles that entered a particular unit are separate categories. Sources

Development and competing programs

Walter Wilson's medium design developed during 1917–1918 alongside other attempts to improve mobility and crew arrangements. Accounts place the start of design work in July 1917 and the prototype in 1918. It contrasts this effort with the Tritton and Rigby Medium Mark C, rather than treating the two as successive names for one project. Sources

The chronology associates prototype and trial work with Metropolitan and with Wednesbury. Individual serials recur in the photographic and film record, but their identification remains unconfirmed against the original captions and trials documentation. A film reference, a construction date and a service-entry date cannot be combined into a single introduction date. Sources

Large orders discussed during the war were not equivalent to final output. A mid-1918 figure of 450 and still larger program figures describe procurement expectations that changed as the war ended and priorities shifted. Canceled orders and proposed changes did not constitute completed production. Sources

It identifies the companies associated with the program and its canceled or reduced portions, while leaving uncertain allocations visible. The later preference for the competing medium design is part of the procurement story, not proof that every criticism of the Mark B was demonstrated in combat. Sources

Layout, protection, and crew working space

The Mark B placed its fighting compartment toward the front in a fixed raised structure, with the engine behind a partition. The shape and position of this compartment distinguish it from both the smaller Medium Mark A and the long sponson-armed heavy tanks. There was no rotating main turret. Sources

The protection scheme is commonly summarized as approximately 6–14 mm, with values needing to remain attached to their source and location. The hull and track arrangement reflected the continuing importance of trenches and broken ground, but compactness imposed restrictions on interior space. Separating the engine could reduce some direct exposure to machinery without making the crew compartment spacious or comfortable. Sources

Accounts describe a four-man crew. Observation, driving and the distribution of machine guns through available mountings imposed coordination demands. The presence of more mounting positions than weapons does not demonstrate that every opening was occupied simultaneously. A photograph with empty mounts is evidence of the photographed condition, not necessarily the tank's intended full issue of weapons. Sources

Weapons, engine, and mobility

The built vehicle carried machine guns, commonly described as four weapons that could be moved between seven positions. Sources differ over specific weapon types and ammunition allowances. The article therefore distinguishes installed gun count, available ports and alternate equipment rather than converting seven openings into seven standard guns. Sources

A gun-armed Male was proposed, but its weapon and arrangement belong in the project portion of the family tree. It cannot lend an imaginary combat capability to the manufactured machine-gun tank. Other equipment claims, including smoke devices and particular signaling arrangements, remain unconfirmed before being treated as standard fittings. Sources

A Ricardo four-cylinder engine, usually rated at about 100 horsepower, drove a Wilson transmission. With the tank commonly described around eighteen tons, mobility remained modest. An often-quoted speed near 6 mph is a design or road-performance reference, not proof of sustained operational movement over battle-scarred ground. Sources

The tracked chassis lacked the kind of sprung suspension later associated with fast medium tanks. Its long track path and forward fighting compartment created trade-offs in obstacle crossing, turning and internal arrangement. Trial fittings such as unditching equipment describe particular vehicles and dates rather than a universal production standard. Sources

Production, acceptance, and postwar service

Published accounts give a distinction between total manufacture and Army acceptance. The relationship between 102 constructed and 45 accepted Medium Mark B tanks remains disputed. It cannot be resolved by subtracting two totals and inventing a complete disposal history for the remainder. Sources

Metropolitan, North British Locomotive and Coventry Ordnance Works appear among the principal industrial participants, with other planned work affected by cancellation. A single overall total does not explain where tanks were completed, how their equipment differed, or which works delivered the accepted vehicles. Sources

There was no First World War combat record. The limited subsequent history includes British employment associated with Ireland and accounts of vehicles connected with Russia and Latvia. Numbers and acquisition routes differ, including whether two or three vehicles belong in one transfer narrative. Sources

No surviving example is established in the published evidence base. That makes contemporary photographs, drawings and films especially important, but the absence of a known survivor in the available accounts collection is not a fresh worldwide museum inventory. Sources

Trials, illustrations, and historical assessment

The three images serve different roles. The period photograph shows a vehicle with its machine guns absent; the general-arrangement drawing explains the layout; and the small film-related image supplies a trials or demonstration context. Its limited resolution makes it unsuitable as a large header or for confidently identifying small fittings. Sources

The account includes a bridge-crossing film lead. Crossing a bridge during a demonstration is not the same as carrying and deploying a bridge as an engineered vehicle conversion. The cited evidence does not establish a separate completed bridge-layer variant. Sources

The Medium Mark B is best assessed as a late-war attempt to solve a set of competing requirements whose production and service were curtailed by changing circumstances. Its value to the encyclopedia includes the design itself, the industrial choices around it, and the limits of the surviving record. That approach preserves a distinct medium-tank history without supplying it with a battlefield record or standardized variants that The available evidence does not establish. Sources

Photograph and image credit

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

Sources and further reading

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

Overview and classification

Development and competing programs

Layout, protection, and crew working space

Weapons, engine, and mobility

Production, acceptance, and postwar service

Trials, illustrations, and historical assessment

Photograph and image credit

Sources and further reading

Continue exploring