Yet they were cheap enough to be built in large numbers. Typical Main Battle Tanks were as well armed as any other vehicle on the battlefield, highly mobile, and well armored. The Main Battle Tank thus took on the role the British had once called the 'Universal tank', filling almost all battlefield roles. Even reconnaissance vehicles had shown a trend towards heavier weight and greater firepower during World War II speed was not a substitute for armor and firepower. Likewise, World War II had shown that lightly-armed, lightly-armored tanks were of little value in most roles. The World War II concept of heavy tanks, armed with the most powerful guns and heaviest armor, became obsolete since they were just as vulnerable as other vehicles to the new medium tanks. This transition happened gradually in the 1950s, as it was realized that medium tanks could carry guns (such as the US 90 mm, Soviet 100 mm, and especially the British L7 105 mm) that could penetrate any practical level of armor at long range. Medium tanks gradually evolved into the new concept of the MBT.

The next us main battle tank