The most mass produced American tank in WWII was the M4 Sherman. Objectively, this was a very good design. Decent armament and armour, good maneuverability and speed. Most important of all, it was easily repaired. The Americans built 50 thousand Shermans throughout the war. However, in 1943, they first met Tigers and Panthers in Italy and Africa. After meeting with this zoo, American commanders' faces turned very pensive, and not very amused.
To help the Sherman, the M26 Pershing was developed toward the end of the war. It could fight with German tanks as an equal, but since the first Pershings appeared in February of 1945, they didn't have much time to prove themselves. Pershings fought as a part of the 12th tank group.
The Pershing was, in many ways, superior to the Sherman, but had its drawbacks. The Pershing had the same engine as the M4A3, but was 10 tons heavier. Because of this, it had poor maneuverability and off-road capability. Its 120 km range was laughable when held up to the standards of modern war. High command issued a verdict: the M26 needed improvement.
A new tank began development in 1948. The reason for this delay was that the Americans were enamoured with atomic bombs and the methods of their delivery. A war that could be swiftly ended by a handful of planes carrying such bombs seemed much more attractive than tank and infantry battles. However, the failing relationship with the Soviet Union rid the Americans of these illusions. You can't throw around atomic bombs in Europe all willy-nilly, civilization won't appreciate it. As for valuable targets in the USSR itself, just try getting to them. Americans had to come back to Earth and modernize the M26. However, the resources that were dedicated to this project were scarce.
In May 1948, the first prototype was shipped to Aberdeen. It had a more powerful engine and a more reliable transmission than the M26. It was suggested that the gun be replaced, but the same M3 gun ended up on the tank, with a few modifications. Prototypes were tested until July 1949, after which the tank was accepted for general production. It was named "Patton", after the American general Joe Patton.
The M46 was very similar to its predecessor, and serves as a good example of what can be achieved with very tight financial limitations. The Patton's superior engine and transmission did not fully get rid it of the Pershing's "illnesses" of poor maneuverability and range. Contemporaries remark that the Patton had difficulties with climbing hills. The new engine exhausted the gas tanks within 120 to 145 kilometers. This was not enough for any maneuvers. Additionally, the Patton's 44 ton mass could not be supported by a large number of European bridges. Its size was greater than both the European and Soviet railroad standards. This meant that whoever had to deal with the logistics would have a hard time; the tank could not be shipped everywhere.
The armour and armament were nothing special either. The 90mm gun was weaker than British and Soviet analogues. It was an effective weapon against late WWII tanks, but it had great difficulty with the tanks of the potential enemy. A T-54 Model 1949 was impenetrable with standard AP rounds, and subcaliber rounds could only penetrate it at short distances, at angles close to normal. The Patton's armour could not protect it from 100 mm shells, and 85 mm shells, while not guaranteeing penetration in the front, could easily penetrate the side. Without going too deep in the details, let us say that the only Soviet tank that the Patton was a deadly opponent to was the T-34-85. In order to defeat more modern armour, the Patton would have to work hard, taking up tactically superior positions and aiming for sides, rears, or use expensive subcaliber ammunition.
The only war the M46 fought in was the Korean war. In the fall of 1950, two American tank battalions with Pershings and Pattons supported the advance of American and South Korean forces. Here, what was described one paragraph above was proven: after engaging with 8 T-34-85s and one SU-76, Pattons of the 6th armoured corps defeated them with no losses. Over 12 battles where Pattons were used, 12 total T-34-85s were destroyed.
After more advanced M47 and M48s were built, M46 Pattons were removed from the regular army and transferred to the National Guard or reserves. A number of these vehicles remained in service in South Korea. In 1957, the M46 Patton was officially added to the list of obsolete vehicles. In the early 1960s, all M46 Pattons were either scrapped or handed off to serve as either museum exhibits or practice targets.
A number of M46 tanks survive to this day, including one at the Kubinka museum.
Original article available here.