Overview
The Holt Gas-Electric Tank was an American experimental armored vehicle developed through cooperation between Holt and General Electric. It combined a gasoline engine with electrical transmission to the tracks, placing a substantial gun in a box-like armored hull. The references identify one prototype and no series production or operational deployment. Sources
Names associated with the project include Vehicle A, Model E and Gas-Electric Monitor. The names refer to the same experiment rather than several distinct tank designs. The steam-powered Vehicle B and later General Electric gun-mount projects are separate subjects. Similar wording in an published figures, such as “single prototype,” does not demonstrate that two experimental tanks were the same machine. Sources
The vehicle's importance is experimental. It tested an alternative way of transmitting engine power to a heavy tracked vehicle during a period when the United States was trying to establish its tank capability. It did not become a combat counterpart of the French and British tanks used by American forces in Europe, and its projected battlefield usefulness is not established as a service record. Sources
Development and the American requirement
The project grew from an existing industrial combination: Holt's experience with tracked tractors and General Electric's electrical engineering. Reusing that experience did not remove the difficulty of integrating armor, weapons, a fighting compartment and a suitable drive into a single vehicle. The military application demanded more than the ability to move a tractor or a heavy load on favorable ground. Sources
The accounts distinguish a General Electric drawing dated 25 May 1917 from Army-related activity at Peoria in July. A drawing is evidence that engineering work existed by its stated date; it is not a completion or acceptance certificate for the tank. Sources
Accounts place construction toward the end of 1917 and evaluation in early 1918, while broader summaries use the combined range 1917–1918. That broad development period is retained until the trial and completion documentation can be reconciled more precisely. The project proceeded alongside, rather than replacing, American dependence on Allied tank designs and the other domestic experimental programs. Sources
Hull, armament, and protection
The fighting arrangement was a fixed armored body without a rotating main turret. A gun mounted in the bow provided forward fire, while machine guns covered the sides. The gun's restricted mounting made the vehicle's direction of travel important to its field of fire. It cannot be described with the turret characteristics of a Renault-derived light tank. Sources
Accounts associate the main weapon with a 75 mm M1916 pack-howitzer or Vickers 2.95-inch lineage, but retains an unresolved question about the weapon designation and mounting. Two side machine guns are generally described; their exact model cannot be assigned solely from a small external photograph. Ammunition capacity and internal stowage remain insufficiently documented. Sources
A report of five-eighths-inch boiler plate differs in evidentiary meaning from a later summary giving an armor-thickness range around 6–15 mm. Plate thickness alone does not establish ballistic treatment or tested protection. The working description keeps the material claim and the armor summaries distinguishable rather than turning them into a verified armor diagram. Width figures also differ substantially between sources, and a reason for that disagreement has not been established. Sources
The gas-electric drive and its limits
A gasoline engine drove a generator that supplied electric motors associated with the tracks. This electrical transmission differed from a conventional mechanical gearbox and steering system. It was not battery propulsion or a modern hybrid operating system. Sources
Published accounts describe a Holt engine rating around 90 horsepower. Against a vehicle commonly described as roughly 25.4 metric tonnes or 28 short tons, that was a modest power allowance. Some accounts simply say “25 tons,” without resolving the unit. Sources
The trial narrative emphasizes limited mobility, difficulty on slopes and obstacles, and cooling problems. A level-ground speed often quoted around 6 mph does not establish an equivalent cross-country speed. The frequently repeated range around 50 km is less securely supported. The central technical question was whether the entire power and cooling arrangement could move the armored vehicle reliably through demanding terrain, not merely whether the motors could turn its tracks. Sources
A crew commonly given as six, with another account using seven, occupied the hull around weapons and machinery. The cited accounts do not firmly establish exact stations, equipment and ventilation arrangements. No standard radio installation, dependable maintenance interval or detailed operational endurance record is established in the cited sources. Such gaps remain explicit rather than being filled with specifications borrowed from later American tanks. Sources
Evaluation, production, and service boundaries
The record supports one experimental machine, not an accepted production model. Manufacturing plans and the existence of an armed prototype can be distinguished from serial orders and deliveries. The evaluation did not lead to a service fleet, foreign operators or a wartime deployment. Sources
Because the tank never entered combat, it has no battlefield loss record or authentic combat-crew testimony. Its perceived strengths and weaknesses belong to engineering assessment and the reported trials. The published discussion of vulnerability or difficult crew working conditions remain analytical where it is not tied to a direct test observation. Sources
The prototype was ultimately disposed of, but the precise scrapping date is not securely established in the evidence assembled here. That uncertainty is preferable to a neat but unsupported final date. Its place in the production history is consequently a single unsuccessful experiment within a much broader American search for suitable armored vehicles. Sources
Legacy and historical evidence
The Holt experiment illustrates both the attraction and the burden of electrical transmission in an early tank. Separating engine operation from the direct mechanical drive to each track offered an alternative control arrangement, but added electrical equipment, cooling demands and integration work. Published accounts describe the outcome as a lesson in whole-vehicle balance rather than proof that one transmission principle was inherently unsuitable for every later tank. Sources
The two period photographs show the hull and running gear from the side and the bow with its gun opening. They do not reveal a complete internal layout of the engine, generator, and motors. Sources
Its use as a source and its use as a published illustration are separate decisions. No imagined operating or combat scene is needed to explain the prototype. Sources
Sources and further reading
Background reading and references. Each photograph has its own source and credit.
- Osprey 2024 — Osprey Publishing, “US Tanks of WWI,” blog/article, July 25, 2024. — Accessed 2026-05-30.
- Zaloga/Osprey 2017 — Steven J. Zaloga, Early US Armor: Tanks 1916-40, Osprey New Vanguard 245, 2017. — Accessed 2026-05-30.
- MIS Story — Google Arts & Culture, “When America Built An Electric Hybrid Tank,” with media from Museum of Innovation & Science. — Accessed 2026-05-30.
- MIS Drawing — Google Arts & Culture asset, “GE Hybrid Tank Drawing,” creator General Electric Company, Museum of Innovation & Science. — Accessed 2026-05-30.
- MIS Photo — Google Arts & Culture assets, “GE Hybrid Tank” and “GE Hybrid Tank, 1918,” creator General Electric Company, Museum of Innovation & Science. — and — Accessed 2026-05-30.
- MIS Photo — Google Arts & Culture assets, “GE Hybrid Tank” and “GE Hybrid Tank, 1918,” creator General Electric Company, Museum of Innovation & Science. — and — Accessed 2026-05-30.
- MilitaryFactory 2018 — MilitaryFactory.com, “Model 1917 Holt Gas-Electric Prototype Military Vehicle,” last edited Sept. 28, 2018. — Accessed 2026-05-30.
- Tank-AFV — Tank-AFV.com, “Holt Gas Electric Tank.” — Accessed 2026-05-30. Further reading; not independently consulted.
- Caterpillar 1925 Merger — Caterpillar official history page, “The Merger of Holt & Best.” — Accessed 2026-05-30.
- Wikimedia A — Wikimedia Commons, File:Holt Gas Electric Tank.jpg. — Accessed 2026-05-30.
- Wikimedia B — Wikimedia Commons, File:Holt prototype gas electric tank.jpg. — Accessed 2026-05-30.
- Landships lead — Landships.info, “Holt Gas Electric Tank,” source referenced in Wikimedia and in secondary summaries. — Access attempted 2026-05-30. Further reading; not independently consulted.
