The T2 medium tank resembled an enlarged version of the T1E1 light tank. It carried a 47mm gun in the turret and a 37mm gun in the hull. Among its more unusual features was the location of the fuel tanks on the exterior of the hull above the suspension.

The lack of funds for modern tank development did not deter at least one engineer from offering the US Army his own designs. J. Walter Christie was a colorful and eccentric automobile designer who had built over a dozen self-propelled artillery mounts for Ordnance between 1918 and 1919. Christie’s most famous innovation was the “convertible” suspension. Christie came up with the idea for a hybrid suspension that utilized large road-wheels for road travel; on reaching the battlefield, a set of tracks would be mounted for cross-country travel. As a result, the tank carriers would no longer be needed, saving a great deal of money. Christie’s Front Drive Motor Company in Hoboken, New Jersey, received a contract for its M1919 convertible tank in November 1919 that was delivered in February 1921 to Aberdeen Proving Ground (APG) in Maryland. The idler and drive sprocket at the ends of the suspension were quite large, while in the center was a bogie with a pair of small road-wheels. The M1919 convertible tank had a simple cylindrical turret with the standard 2.24in M1920 gun, a derivative of the British 6-pdr. The trials in the wheeled configuration were unimpressive since the large road-wheels were rigidly mounted without springs. It was woefully underpowered and barely able to reach 7mph. In April 1921, after two months of disappointing tests, Christie asked for the trials to be suspended so that he could improve the design. Ordnance agreed and after nearly a year, the tank was returned to APG for further trials. Now called the M1921 convertible tank, Christie had modified the front roadwheels with substantial springs for a smoother road ride. The hull had been completely reconfigured with the turret replaced with a fixed barbette. The 2.24in gun was mounted in the bow, and two machine guns were placed in ball mounts in the forward part of the superstructure. Although the alterations did improve the automotive performance, the Army felt that the tank was still underpowered, that its maneuverability was poor, and that the tank was mechanically unreliable.

Ordnance developed a strong distaste for working with Christie. The designer regarded himself as a genius and his designs beyond reproach. He often refused to make changes requested by Ordnance. He did not have the perseverance or patience to convert an intriguing design into a functional and reliable machine. The M1921 convertible tank was retired to the APG museum in July 1924, having cost the US Army some $82,000 not counting test costs. Near bankruptcy, Christie sold off his present and future patent rights for vehicle designs to the Army for $100,000 and reorganized his company as the US Wheel Track Layer Corporation in Rahway, New Jersey. Chief of Ordnance Maj Gen Clarence Williams complained that the Army had paid Christie $839,000, netting the inventor a large profit while the Army did not have a single successful vehicle in service based on a Christie design.

Corps of Engineer concerns over the weight of the T1 medium tank led to the start of the new 15-ton T2 medium tank in 1926. Lack of funding delayed construction until 1929. Designed by Harry Knox and built by Cunningham, it resembled an enlarged T1E2 light tank. It had thicker armor and was armed with a 3-pdr (47mm) naval gun. It also had a 37mm gun in the right hull front, but this was quickly replaced with a .30cal machine gun since the gun mount interfered with the turret crew. With a 312hp Liberty aircraft engine, it had a very peppy performance with road speeds up to 25mph. Nevertheless, the T2 quickly disappeared due to Infantry distaste over front-mounted engine designs, engineer complaints about its weight, and the appearance of the rival Christie tank.

After the failure of his M1919 and M1921 tanks, Christie spent several years trying to perfect his convertible suspension. The new design, patented in April 1928, used identical large road-wheels on all stations except the idler and drive sprocket. When the track was removed, the last road-wheel station was powered by a chain-drive off the drive sprocket while the front roadwheel steered the vehicle. The suspension used large helical springs, mounted in protected tunnels within the armored hull, which provided a particularly smooth ride compared to the suspensions that predominated in tank design at this time. To address the Army’s criticism of the sluggish performance of the M1921, Christie used a surplus 300hp Liberty aircraft engine, which he claimed would permit a road speed of 70mph on wheels and 42mph on tracks. The M1928 was not a refined tank, having a bow-mounted machine gun that interfered with the driver. In addition, its flashy performance was due in part to its light weight of about 5 tons made possible by the use of thin sheet steel instead of armor. Christie dubbed the new tank variously the M1928 and M1940, the later designation chosen to show that it was a decade more advanced than any contemporary tank design.

Christie’s M1928 tank was first displayed to the public on July 4, 1928. It appeared at a fortuitous moment when there was a groundswell from younger Army tank enthusiasts beginning to challenge the lethargy and doctrinal orthodoxy of the past decade. In 1927, Secretary of War Dwight Davis witnessed Britain’s Experimental Mechanized Force at Aldershot during an official visit to the UK. On his return, he instructed the US Army to conduct a similar exercise, and this began in the summer of 1928 at Camp Meade. The new T1E1 light tanks proved to be reliable performers compared to the decrepit WWI-era tanks. Nevertheless, many younger officers were concerned that they offered little advance over the Six-Ton tank. In contrast, the performance of Christie’s “wildcat” tank seemed miraculous and offered the technological promise of an escape from the horrors of static trench warfare and a new dawn of mobile offensive warfare.

Like many entrepreneurs, Christie was fond of publicity stunts. To show his tank’s superiority over the Army’s T1E1 light tank, he made the same trip from Fort Meade, Maryland, to Gettysburg, Pennsylvania, in November 1928 with an average speed of 28 miles per hour compared to 10mph for the Ordnance tank. Patton and some of the young Cavalry firebrands recommended that the Christie vehicle be acquired as an armored car, suggesting that it would be particularly useful in patrolling the border with Mexico. On February 19, 1929, Secretary of War Davis directed Ordnance to purchase the M1928 in an armored car configuration and modest funds were approved in the Fiscal Year 1929 (FY29) budget. Disdainful of the Ordnance bureaucracy, Christie provided the M1928 at no cost to the Tank School at Fort Meade for testing but ignored Ordnance’s May 1929 request for bids. As a result, the allotted funds reverted to the Treasury, delaying any purchase for at least another year until funding could be re-approved by Congress. Christie belatedly responded in July 1929 that he had spent $382,000 on the project and so he wanted to sell eight of the tanks at a cost of $82,750 each, which amounted to a development cost of $47,750 each plus the actual manufacturing cost of $35,000 per tank. This was an impossible sum at the time, particularly after the advent of the Great Depression late in 1929.

Christie had been soliciting bids from foreign governments at the same time as his promotions to the US government. A Polish purchasing mission was offered one tank for $30,000 plus a further $90,000 for manufacturing rights, and Warsaw submitted a down payment. The Soviet Union was also bidding for the tank and on April 28, 1930 purchased two M1930 tanks at a cost of $30,000 each, plus $100,000 for manufacturing rights.

Changes in Army leadership roiled the negotiations. The new Army Chief of Infantry, General Stephen Fuqua, was very supportive of acquiring the Christie tanks and as a result, the Ordnance Technical Committee on February 13, 1930 recommended the purchase of six M1928s in a tank configuration with turret. The $250,000 in the FY31 budget earmarked for the purchase of six to eight Cunningham T1E2 tanks was redirected to the Christie tanks instead. The incoming Chief of Ordnance, Gen Samuel Hof, was an old Ordnance hand who had been involved in the squabbles with Christie in the early 1920s. Based on a critical report from tank expert Capt John Christmas, Hof was skeptical of the durability of the Christie tank and wanted to acquire only a single tank for trials before buying any more. In June 1930, the Army Chief of Staff, Gen Charles Summerall, agreed with Hof. Christie was informed that his May 1930 bid for six convertible tanks and a new armored car had been rejected. Instead, he was asked to make an offer for a single tank. Christie responded that he would sell a single tank for the exorbitant price of $135,000, and further angered the Army officers involved in the negotiations by claiming that he had “spies” in the Army and government who kept him informed of the inner workings of the negotiations. He also threatened to use his political connections in Congress to pressure the Army into agreeing to a large purchase.

With the end of the fiscal year approaching and the FY31 tank funding about to revert back to the Treasury again, Christie acquiesced to a lease deal. Contract Word 89, valued at $55,000, was signed on June 28, 1930 with Christie promising to deliver a single convertible tank for trials purposes while the Army would provide the Liberty engine and a suitable turret. The contract mandated a September 1930 delivery date.

Christie was unable to make the deadline since he was already behind schedule on the delivery of the two Soviet tanks; he reneged on the Polish contract in October 1930. He dispatched the two Soviet “commercial tractors” on December 24, 1930. The Army learned of Christie’s duplicity as well as the much lower price he was offering to foreign buyers, further souring relations. The American M1930 Christie tank was delivered behind schedule to APG on January 19, 1931. The Liberty engine broke down after two days of testing, further delaying the trials. The powertrain was a constant source of problems on the Christie design since the engine was too powerful for the transmission; the Soviets had the same problem.  

Egged on by Christie and his many supporters in the Army, Representative Henry Barbour, the chairman of the House sub-committee on appropriations, held extensive Congressional hearings on the Christie tank in December 1930. Col Hiram Cooper, commandant of the Infantry Tank School, strongly praised the Christie tank, as did Sereno Brett, a decorated World War I tanker and executive officer of the Experimental Mechanized Force at Fort Meade. Capt Llewellyn Tharp, who had commanded a company of American Mark V tanks in France in 1918, gave extensive testimony why the Christie tank was so much superior to Ordnance’s T1E1, which he had also tested.

Congressional pressure as well as support for the Christie tank from the Infantry and Cavalry branches forced Ordnance to purchase a larger batch of Christie tanks. Competitive bids were opened on June 4, 1931 and submissions were received from Christie and Nicholas Straussler from Britain. With Barbour’s political support, it was a foregone conclusion that Christie would win the bid. On June 12, 1931 Christie was informed that his firm had won the negotiations and would receive $241,500 in FY32 for seven convertible tanks.

Testing of the new serial production tanks began in December 1931. Of the seven Christie tanks in Army hands, three were designated as T3 medium tanks and allotted to the Infantry at Fort Benning. The remaining four were designated as T1 Combat Cars and sent to the Cavalry at Fort Knox. The first tank used a chain-drive to power the rear wheel when in road travel, but Christie switched to a gear drive on the remaining six tanks, leading to a change of designation to the T3E1 medium tank. The tanks were handcrafted and different problems cropped up on different tanks. Christie spent far more time on “lawyering and lobbying” and not enough time on quality control at his plant. Furthermore, he resisted Ordnance efforts to make improvements on designs which he regarded as unquestionably flawless.

The Infantry wanted at least five tanks to create a normal tank platoon for field experiments. They also wanted a number of significant improvements, including a wider hull to accommodate a four-man crew. As a result, in October 1932, the Army issued a contract bid for five more tanks designated as T3E2. Christie was unwilling to make such extensive changes, and became infuriated when Ordnance sent the bid requests to more than a dozen companies. He believed that he still controlled the patent rights, ignoring previous Army payments. Ordnance anticipated legal action and had already been assured by government lawyers that a tank derived from the Christie concepts was within the Army’s legal rights. Christie refused to participate in the bidding and American LaFrance in Elmira, New York, won the contract on December 2, 1932 for $146,000 for five T3E2 tanks.

Christie began a political campaign to get the contract annulled, which dragged on for several years. He had alienated Gen Hof, and many of Christie’s supporters in the Army came to realize that the convertible tanks were poorly made. They quickly became “hangar queens,” requiring constant maintenance. The diary of Robert Grow, later commander of the 6th Armored Division, recalled the problems with the new tanks: “Had three Christies running this AM. Took them out for rehearsal. Two promptly broke down. No. 3 Christie broke a crankshaft and camrod and tore the crankshaft open. A mean job. 19th Ordnance is pulling the engine.” Ordnance publicized the fact that the Army had to spend more than $38,000 to rectify problems on the Christie tanks in 1932 due to inherent defects.

In the end, the US Army refused to have any further dealings with Christie, and his company went into receivership in 1934. Christie was saved from bankruptcy by a request from Morris Motors in October 1936. British military attach├ęs in the Soviet Union had seen a display of the BT-5 tanks in 1936 and there was Army interest in a British Christie tank. Christie still officially owned the Contract Word 89 tank and delivered this to the UK as a “farm tractor” plus manufacturing rights for $320,000. This led to the A-13 and a subsequent line of Cruiser tanks such as the Covenanter, Crusader, Centaur, and Cromwell.

The American LaFrance T3E2 bore a family resemblance to the Christie design except that the hull had been widened to accept a four-man crew. In many ways, this paralleled the Soviet experience with the BT series that had evolved into the A-20, later leading to the T-34 tank of World War II. The Liberty engine used on the Christie tanks was replaced by a 435hp Curtiss D-12 aircraft engine that provided a maximum speed of 58mph on wheels and 35mph on track. New forged link tracks with a shorter pitch were used that reduced the tendency of the tank to shed its track compared to the archaic plate tracks of the Christie tank. The T3E2 suffered the same inherent problem of the Christie design, mating too powerful an engine with too delicate a transmission and final drive. Clutch-and-brake steering was inadequate for such a powerful powertrain. All five tanks had improvements and were designated as the T3E3 afterwards.

The next attempt to redeem the Christie design was the T4 convertible tank, designed by Knox’s team at RIA. To get around the powertrain problems, a less powerful 268hp Continental engine was used, with a new transmission with controlled differential steering. These tanks proved to be the most successful of the Christie-inspired tanks and also the most numerous, with 19 produced at RIA in 1936 and 1937. Three of these were built in the T4E1 configuration, which used a barbette configuration instead of a turret. Ordnance recommended standardizing these tanks in February 1936, but this was rejected on the grounds that they were not better armed or armored than the M2 light tank, but cost twice as much. This issue was raised again in 1939 and as a result they were designated as the M1 medium tank. This design might have evolved into a modern medium tank as occurred in the Soviet Union with the T-34. However, the Infantry branch was complacent about the need for greater firepower and improved armor due to its antiquated tank doctrine. The Cavalry wanted the T4, but were unable to buy any due to budget constraints.