---
The Holt 150 Ton Field Monitor, 3 Wheeled Steam Tank

Almost no data survives on this strange vehicle built by Holt sometime between 1916 and 1917. It is known that it really existed, and it moved about 50 feet before becoming stuck at Aberdeen Proving Ground. Twin two piston steam engines provided power (one engine devoted to each large wheel). Records do not indicate which end was the front. At 150 tons, this would have been the largest, and heaviest vehicle built in that era. Most likely TANKS! considers this to be a error in the archives and most likely the tank weighed 15 tons or the 150 ton moniker was an effort to hide the design from would-be spies.

Another source states that the vehicle was built by Holt and was called the "Three Wheeled Steam Tank". It was the 3rd tank to be designed in the United States and was completed in 1918. The hull was carried at the front by two 8' diameter tractor wheels and the rear of the vehicle was supported by a triple disc steering roller to which was attached a small steel plate for trench crossing. Each front drive wheel had it's own power unit which consisted of a Doble 2 cylinder 75hp engine and kerosene fired boiler. Main armament was a 2.95" mountain howitzer mounted low in the front. a .50cal Browning HMG was carred in a ball mount on the hull sides. The stated weight was a more believeable 17tons.

---
The Holt Gas Electric

Built in joint cooperation between Holt and General Electric this tank is probably the first U.S. vehicle ever designed from the ground up (not an adaptation of an existing machine) to be a tank.

---
"Steam Tank, Tracklaying"

Built by the Army Corps of Engineers in conjuncton with Stanley Steamer, this tank was intended to attack enemy strong points with an attached flamethrower and act as a battering ram if needed. Fueled by kerosene, powerful twin 500hp two cylinder steam engines powered a track apiece. James Merrick of the Stanley Museum advised TANKS! that the engines allegedly came from "two Unit Railway Car engines and boilers, manufactured by the Stanley Motor Carriage Company in Watertown, Massachusetts, the makers of the Stanley Steamer automobile." Further he informed me that "there is a legend that this tank was driven about the streets of Boston as a demonstration during a Liberty Bond Drive, only to break down in front of the Boston Public Library in Copley Square." Eventually a 35hp gasoline engine was added which gave 1600psi to the flamethrower because the steam engines could only provide 700psi. A two-speed forward and two-speed reverse transmission was provided. No suspension was used, but the tracks were 24" wide. Accounts state that this tank arrived in France in 1918, however, the war ended before any meaningful tests could be carried out.

------------
British Mark 4

There is evidence of Americans training in England and using the British Mark 4 tank in combat in France, but, it appears that photographic evidence of Americans actually using them are scarce. The vehicle shown above is one that was sent to the United States for testing and is shown here at Aberdeen Proving Ground. The female in the picture above was given to Caterpiller after WW1 as a gift. Caterpiller displayed it in parades until WW2 when it was given for scrap in a war effort drive for scrapmetal.

British Mark V

There is evidence of Americans training in England and using the British Mark 5 tank in combat in France, but, it appears that photographic evidence of Americans actually using them are nil. The vehicle shown above is one that was sent to the United States for testing and is shown here at Aberdeen Proving Ground in 1929. 12 of these units were used by the 301st Tank Battalion in France.

------
British Mark V*

Here is a rare find. A real Mark V* tank that was owned and operated by the US 302 heavy tank battalion in France. This tank came home with the battalion after the war and can claim ownership to the title of the worlds first armored personnel carrier. The number on the tank is a number from the series as applied to the Mark V* by the army, THOUGH, it is not the actual number of the tank, that number is long since lost. When the tank was restored the real number had faded so badly that it was unreadable according to museum staff member Charles Lemons. The interior is somewhat gutted but in clean condition. Sadly the engine is gone though the transmission remains. The tracks do not really move anymore and are somewhat frozen in place (a job for WD-40) as when the tank was pushed into the building the tracks slid on the flooring rather than moved.

Mark VIII "Liberty"

------

---

The T1 Project

In 1940, the War Department decided that a heavy tank was again needed for the United States and thus began the T1 Project. The blueprint called for a heavy tank with no less than four turrets in a true land battleship design. Two of them would have carried a 75mm gun a third with a 37mm, a fourth with a 20mm and this does not include multiple machine guns! Fortunately, cooler heads prevailed and the tank looked much different by the time it was off the drawing boards.

The T1 was only an engineering exercise (thank goodness). Actually, the first tank to be produced in this series was the T1E2 (top row). Built at Baldwing Locomotive Works and ready September 1941, the tank was initially unarmed. The T1E1 is shown in the middle row. The T1E3 is the bottom. Due to changing requirements, the T1E4 was never actually built (except on paper). The T1E2 became the M6 (below) and the T1E3 became the M6A1 (also below).

---

------

---
M6, M6A1, M6A1E2

Though never deployed in battle, this tank did see service in the propaganda war. Captured documents after the war with Germany showed that they had worries about America's "Super Tank" and devoted time, effort, and money into the discovery of counter measures. At the time of concept and first production, this tank was considered the most powerful in the world. The M6, due to teething problems, would never see actual service in the American army though. Doubts existed as to it's mechanical reliability and there were fears that the tank was too heavy for actual operational duties. This was to be seen in the deployed German Tiger. The Tiger was a real battle winner when it wasn't:
1. broken down (Tigers had poor mechanical reliability and were hard to recover).
2. late to arrive because of low speed.
3. out of fuel.
4. able to get past rivers with bridges that could not support it's weight.

The M6 was in production at Baldwin Locomotive Works in December 1942 and was undergoing tests by the spring of 1943. Tests showed that the design was poor from the ergonomics point of view. Controls and weapons controls were awkward and inconvenient to operate. The M6 and M6A1 were identical except for the manufacture of the hulls. The M6 was cast and the M6A1 was welded.

The M6 and M6A1, with the exception of one M6A1 produced at General Motors Fisher Body Division, were all built by Baldwin. A total of 43 vehicles were built there (eight M6, twelve M6A1, twenty T1E1). At one point, 230 T1E1 were ordered, but this was cancelled as operational needs showed that commanders would rather have two 30 ton mediums than one 60 ton heavy tank. All important dimensions, like armor thickness and size were identical to the M6. The purpose of constructing a welded model was to test building this type for manufacturing plants that could not produce cast hulls.

A variation to the design was the M6A2E1 in which only one was constructed (bottom row, right photo). This tank was built to a specific need: to break tough defensive positions in Europe. The T5E1 105mm cannon was used and the turret ring increased from 69" to 80". The vehicle's height went up to 11' 5" as a result of the new turret. and the length (with the gun) went to just under 37'. A goal was to build 15 of these monsters and ship them quickly to the European theater. European commands considered this tank and promptly rejected it. The thought of a 154,000 pound vehicle that could only travel 18mph was considered too difficult to deploy.

One T1E1 survives today and can be seen at the museum at Aberdeen.

---

---

------

The T28 Project

Designed for the final push in Europe. In the spring of 1945, Pacific Car and Foundry Company began work on this 95 ton behemoth. One still survives and can be seen at the Patton museum at Ft. Knox. Armed with a 105mm main gun, five pilots were built with a goal to produce 25. Double tracked, the width of this tank could be reduced by removing the outside track for transportation by rail. The gun had a muzzle velocity of over 3700 fps and could send a projectile nearly 12 miles. Operated by a crew of 4, the only secondary armament this monster had was a turret ring mounted .50cal heavy machine gun and, as a result, required the defender to be exposed. The project was scrapped with the end of the war with only the five pre production models constructed.

------
The T29 Project

In early 1945, the T29 Project was begun to counter the new heavier tanks being fielded in Europe by the Germans. The new Pershing tank, at 45 tons, was not quite "heavy" enough to counter the 70 ton German Tiger II. Not ready when the war ended, it did provide opportunities for testing of engineering concepts in artillery and automotive components. Shown above (from left to right) are the T29, T29E2, and the T29E3. The difference between the T29E1 and T29E2 was the E1 used an Allison 1710ci V12 and the E2 was a upgrade in turret and gun controls. The E3 model had further upgrades in armament and fire control. Most of the basics remained the same in all models. Driving was done by using a "joy stick" as on an airplane. The transmission was GM CD-850-1 which provided steering, braking, and variable power flow to each track. Foot pedals controlled the braking function, not the "joy stick".

Last Update: Thursday, February 13, 2003