Thread by @usacac

ARMOR (Part I): No More Tank Corps

We are not quite done with Cavalry yet, but we have a lot more to cover and as we look at Armor and Infantry the lines are about to cross more than once, so let’s start with a bit of Armor history.

We’ve talked about how the National Defense Act of 1920 stipulated that all tanks would only belong to the Infantry, so to get around this Cavalry worked on finding a range of armored cars, combat cars, and scout cars for their missions.

During World War I, we had a Tank Corps, but there was no consensus on where the tank actually fit within the Army.

The National Defense Act of 1920 attempted to address this issue and the decisions made within the Act were based on our experiences in WWI.

“Under the Act’s comprehensive provisions, the Tank Corps was abolished, and tank units were assigned to Infantry, becoming known as ‘Infantry (Tanks)’.”

“Moreover, the Act’s stipulation that ‘hereafter all tank units shall form a part of the Infantry’ left little doubt as to the tank role for the immediate future.”

Between 1918 and 1922, different parts of the @USArmy presented arguments as to why the Tanks should belong to their Branch. This included the Chiefs of Infantry and the (doomed) Tank Corps, as well as the Chief of Ordnance. @MastersManeuver @USAODCorps @ChiefofOrdnance

The War Department issued a policy in the Spring of 1922 that would ultimately hinder tank development. This policy stated that the primary mission of tanks was “to facilitate the uninterrupted advance of the riflemen in the attack.”

In other words, Infantry was the priority and tanks would primarily be used to support them.

Part of the reason this hindered tank development was that the War Department also decided that since this was their primary purpose, we would only need light and medium tanks.

Light tanks would have to be transported by truck and would weigh no more than 5 tons each. Medium tanks were not to exceed 15 tons as that was the general weight capacity of things like railroad cars and highway bridges…

… and “most significantly” that was the max weight capacity of “available Engineer Corps ponton bridges.” @USACEHQ

There were problems, however. Not just with these stipulations but with the ability to meet them.

An experimental 15-ton tank was produced up to the “mock-up stage” but it was not quite able to satisfy the specifications set by the War Department. Other post-WWI light and medium tank designs struggled to meet the specifications as well.

“In reality, it was simply impossible to build a 15-ton vehicle meeting both War Department and Infantry requirements.”

By 1926, the War Department General Staff reluctantly agreed to the development of a 23-ton tank but added the instruction that efforts were to continue to find a satisfactory 15-ton vehicle to meet the original specifications.

The new Branch Chief of Infantry decided that a light tank that was truck-transportable was exactly what the Infantry needed, much to the chagrin of @USArmy Tankers who argued that we really needed “more heavily armed and armored medium” tanks. @jr_liscano

“The net effect of the Infantry’s preoccupation with light tanks and the limited funds available for tank development in general was to slow the development of heavier vehicles and, ultimately, to contribute to the serious shortage of mediums at the outbreak of World War II.”

Those we did have would prove inadequate, but we'll get to that another time.

Debates amongst Army and War Department leadership were not the only things affecting tank development during the Interwar Years. The designers and manufacturers had disagreements as well.

J. Walter Christie, a private manufacturer, tested, designed, and developed a new model of tank that had the “ability to operate both on tracks and on large, solid-rubber-tired bogie wheels. The tracks were removable to permit operation on wheels over moderate terrain.”

This new model also featured the Christie Suspension, which has independent springs for each wheel. This offered some advantages, including the ability to “attain speeds of 69 miles per hour on wheels and 42 miles per hour on tracks” but not with the tank fully equipped.

“To the Infantry and Cavalry, the Christie was the best answer to their need for a fast, lightweight tank, and they were enthusiastic about its convertibility.”

This video shows footage of the M1931 Christie Tank, which was briefly used by both Infantry and Cavalry in the mid-1930s.

The Ordnance Department recognized the appeal of these features but found the Christie model “mechanically unreliable and that such dual-purpose equipment generally violated good engineering practice.”

This argument between Christie, the @USArmy Ordnance Department, and other designers and engineers continued for nearly the entire Interwar Period. By 1938, the idea of a convertible tank (optional tracks or wheels) was completely abandoned.

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