Medium Tank M1921

Yhdysvalloissa valmistettiin 1920 keskiraskas panssarivaunu, jonka rakenne noudatti korkea telakoneiston linjaa, tai vamistustapaa kuten Char vaunuissa.

Tämä vaunu suunniteltiin ja rakennettiin Rock Island Arsenal tehtassa, valmistui 1921 joulukuussa ja sitä testattiin Aberdeessä 1922 helmikuun aikana. 

Vaunun telasto, jousitus ja aseistus perustui brittiläiseen toiminta-periaatteeseen. Sopivan mottorin löytämisessä oli hankaluuksia, monia vaihtoehtoja kokeiltiin, 
samoin tornin aseistuksen kanssa ja viimein valittiin englantilainen 2 paunan tykki.

Malli: T1 Medium Tank.
Teoreettinen tieto.
Paino:18,6 tonnia
Panssari: 25 mm edessä ja torneissa, 9 mm taistelutila ja katto.
Miehistö: 4 miestä
Aseistus: Yksi 57 mm tykki päätornissa + 1 x 7,62 mm konekivääri.
Ylätorni: Yksi 7.62 mm konekivääri.
Moottori: Murray - Tregurtha 220 hp /1200 rpm (teoreettinen).
Telaleveys: 45 cm.
Nopeus: 16 km/h maastossa.

Kokeiltavassa vaunussa ollut Murray-Tregurtha pikaveneen moottorin tehot eivät käytännössä vastanneet annettuja suoritus-arvoja, vaan jäivät paljon heikommiksi.
Moottorin teho jäi vain 195 hv / 1250 rpm, joka vaikutti vaunun maantie-nopeuteen.
Moottori kokeiluita oli useita ja lopulta valittiin lentokoneen Liberty 338 hp V-12, 
jolloin vaunun nopeus nousi 26 km/h.

Kaikesta huolimatta tätä panssarivaunua rakennettiin vain tämä yksi prototyyppi vaikka testaukset jatkuivat vielä vuosia, hyvin monia erilaisia vaihtoehtoja kokeillen,
vaunujen sarjavalmistusta ei koskaan aloitettu, mutta tämän panssarivaunun 
rakentamisesta saadut kokemukset ja suunnittelun tiedot jäivät avokkaina tietona arkistoihin. Testaukset päättyivät 1926 vuoden aikana, vaikka moni testaukseen osallistunut oli sitä mieltä että tämän panssarivaunun kehittämistä olisi pitänyt edelleen jatkaa. 

Vaunusta kehitettiin myös rinnakkais-malli M1922 joka erosi hieman rakenteen sekä siinä käytettävän moottorin osalta, mutta tästä ehkä joskus toisella kertaa.
----------------------------------------------------------------------------------------------------------------
Although the tank of World War I was slow, clumsy, unwieldy, difficult to control, and mechanically unreliable, its value as a combat weapon had been clearly proven. In addition to the light and heavy categories of American-produced tanks of World War I, a third classification, the medium, began receiving attention in 1919. The meaning of the terms light, medium, and heavy tanks changed between the wars. During World War I and immediately thereafter, the light tank was considered to be up to 10 tons, the medium (produced by the British) was roughly between 10 and 25 tons, and the heavy was over 25 tons. Later in World War II, increased weights resulted in the light tank being over 20 tons, the medium over 30, and the heavy, developed toward the end of the war, over 60 tons.

After the end of the conflict, the U.S. Army was reorganized. In 1919, Pershing recommended to a joint session of the Senate and House Committee on Military Affairs that the tank be subordinated to the infantry. As a result, the 1920 National Defense Act disbanded the unit and reassigned its tanks to the infantry branch, with only two heavy and four light battalions escaping post-war demobilization.

It is interesting to note that both Patton and Eisenhower remained involved in developing the armored arm, which found a temporary home at Camp Meade under Rockenbach's command. In particular, the two men formulated theory and doctrine for the use of tanks in mass formations to achieve breakthroughs and carry out exploitation. They met vigorous opposition to their ideas from senior army officers who favored the use of armor in support of infantry and not as a separate arm conducting independent operations. Congress took this view as well, when enacting the 1920 legislation that dissolved the Tank Corps as a separate entity.

The National Defense Act of 1920 placed the Tank Corps under the Infantry. Patton had argued for an independent Tank Corps, and understood that tanks operating with Cavalry would stress mobility, while tanks tied to the Infantry would emphasize firepower. However, the supply of slow World War I tanks and the subordination of tanks to the infantry branch impeded the development of any role other than direct infantry support, so United States moved slowly in the development of armored and mechanized forces. Not incidentally, funding for tank research and development was also cut to a bare minimum. Patton, convinced there was no future in tanks, applied and received a transfer to the cavalry in September, 1920. Eisenhower got out two years later, in January 1922, when he was assigned to the staff of an infantry brigade in Panama.

The US War Department considered that two types of tanks, the light and the medium, should fulfill all missions. The light tank was to be truck transportable and not exceed 5 tons gross weight and for the medium, restrictions were even more stringent; its weight was not to exceed 15 tons, so as to bring it within the weight capacity of railroad flatcars. Although an experimental 15-ton tank, the M1924, reached the mock-up stage, this and other attempts to satisfy War Department and infantry specifications proved to be unsatisfactory. In reality it was simply impossible to build a 15-ton vehicle meeting both War Department and infantry requirements.

In 1926 the General Staff reluctantly consented to the development of a 23-ton tank, although it made clear that efforts were to continue toward the production of a satisfactory 15-ton vehicle. The infantry decided, too, that a light tank, transportable by truck, best met infantry requirements. 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.