Tanks to Canada
As most of the M1917s and Mark VIIIs had been mothballed, some did get new life in 1940 when many were shipped to Canada to be used in training.5
Still Not Prepared
Even though war had come to Europe, there were still no plans for mass producing engines even as late as 1940.5
The New Armored Forces
The War Department was impressed by the quick German victories in Poland and France and they decided to form the Armored Forces on July 10, 19402,4, with Chaffee as the commander. A week later the I Armored Corps was formed with the 1st & 2nd Armored Divisions1, and there was also the 70th tank battalion.
The armored divisions contained:
- an armored brigade with,
- 2 light tanks regiments with,
- a medium tank regiment with,
- 2 battalion artillery regiment with self propelled 105 mm howitzers,
- 2 battalions of motorized infantry
- an artillery battalion,
- an armored reconnaissance battalion,
- an engineer battalion,
- and divisional service units.
The US Army had about 500 machines in July 1940, and most of these were obsolete.
Tank Development During Early Months of War
In late 1936 the US Army had recommenced the design of a T5 medium tank, but the Ordnance Department favored light tanks.
The T5 was a larger M3 light tank with more armor and firepower. It even shared many components with the M3. In early 1939 many configurations of main armament and machine guns were tested. Towards the end of 1939 the T5 prototypes were standardized as the M2. It's main armament was a 37 mm gun with eight machine guns.5
Chrysler Corporation was awarded the US Army contract on August 15, 1940, to produced 1,000 M2A1 medium tanks. However, reports from Europe resulted in the conclusion that the M2A1 was already obsolete and the order was canceled on August 28, 1940.
Two locomotive companies were selected to produce the M2A1 as it was felt that they had the expertise and machinery to construct tanks.5 Diesel and air cooled aircraft engines were ordered.5
As orders flowed in from Europe it was seen that without major expansion, industry would be left behind as it had been in World War I.5
Initial Production Rates
Initial production plans called for 1,741 medium tanks to be built in a year and a half.5 Soon it was talked about producing ten tanks per day.5 To achieve these goals it was decided to turn to the experts of mass production, the Detroit automobile industry.5
It took less than a month to design a tank arsenal just outside of Detroit.5 This became the Detroit Tank Arsenal.5 It cost $21 million to build.5 Soon it was producing the required 10 tanks per day.5
Since Chrysler was already starting to gear up for production, the US Army changed the order to 1,000 of the M3 medium tanks which hadn't been designed yet.
Some of the features that led to the success of the designs of the U.S. tanks were:
- Rubber-bushed tank track developed in 1930s. This replaced the easily worn all metal pins, with a bin in rubber bushings. This allowed for the pins to last much longer. It was designed by the US Army Rock Island Arsenal and Timken Bearing Co.
- Volute spring suspension was more powerful than leaf, coil, or torsion bar suspensions.
- Compact engines in the rear of the tank which were modified air-cooled aircraft engines.
Tank destroyers were classified as Motor Gun Carriages along with self-propelled artillery. They were intended to be used as primarily hit and run type combat. However, often times they were used as normal tanks which they weren't always suitable for.
Half tracks were used widely by the US Between 1925 and 1930 several Citroen-Kegresse half tracks were purchased from France. In 1930 a license to build them was purchased. The James Cunningham auto company and the US Army Rock Island auto engineering division combined to design half tracks. They had designed several "adapters" by 1935 that could be installed in place of the rear wheels on a conventional auto chassis. In 1939 the Army took a M3 Scout Car and added one of these "adapters" to it. It proved to be very successful. In 1941 the Army standardized on the M2 Half Track Car and M3 Half Track Personnel Carrier.
United States Army Air Forces (USAAF) Born
In June 1941 the United States Army Air Forces command was formed.6
The Army Ground Forces thought that the proper role for tanks was to maneuver on the battlefield and not engage enemy tanks.2 Enemy tanks were to be left to the tank destroyers and artillery.2 As a result, by 1943, there were 106 active tank destroyer battalions.2
However, Ordnance and the Armored Forces felt that the best anti-tank weapon was a tank.2
Even Ordnance and the Armored Forces disagreed on whether to mount 90 mm guns on a new tank to replace the Sherman.2 Ordnance wanted the new 90 mm guns, but the Armored Forces felt that the tank chassis wouldn't be ready in time.2
Army Ground Forces felt that the 90 mm gun would only encourage American tanks to fight enemy tanks.2
These disagreements delayed the design of the M26 Pershing tanks.2
In March 1942, the brigade headquarters were replaced by 2 Combat Commands (A & B).2 Each of them could be allocated different units by the divisional commander, which provided a lot of flexibility. It now contained:
- 2 (32) armored regiments with,
- a light tank battalion2,
- 2 medium tank battalions2,
- an armored infantry regiment2
- 3 artillery battalions with self propelled 105 mm howitzers,
- an armored reconnaissance battalion2,
- an engineer battalion2,
- and divisional service units
- Signals company2
- Maintenance company2
- Quartermaster Truck battalion2
- Medical battalion2
September 1943 Reorganization
- 3 tank battalions2
- 1 light tank company2
- 3 medium tank companies2
- Headquarters company2
- Service company2
- Cavalry reconnaissance squadron2
||July 15, 1940
The divisions were changed to allow for more medium tanks and fewer light tanks in March 1942.1 Two more Armored Corps were formed before the end of the year.
By the end of 1943 the concept of a separate Armored Corps was abandoned in favor of armored units making up part of an all arms team.
A total of 16 armored divisions were formed between July 1940 and March 1943. There were also 65 independent tank battalions by the end of 1944 and 17 amphibian tractor battalions.1
To support the armored divisions large numbers of self propelled artillery, anti-aircraft guns, and half tracks were produced.
Britain, Canada, and the Free French used large numbers of American tanks in Europe.