The 100-ton vehicle was initially designated a heavy tank. It was re-designated as the 105 mm Gun Motor Carriage T95 in 1945, and then renamed in 1946 as the Super Heavy Tank T28.
Only two prototypes were built before the project was terminated
What particularly worried American planners was the Siegfried Line, the long chain of pillboxes and bunkers that guarded Germany’s western border. A 1943 Ordnance Department study concluded that a heavily armed and armored vehicle would be needed to breach those defenses.
“The original concept proposed mounting the new 105mm gun T5EI in a tank with the equivalent of 8-inch frontal armor using the electric drive system developed for the heavy tank T1E1 and the medium tank T23,” according to tank historian R. P. Hunnicutt in his book Firepower: A History of the American Heavy Tank. “The high velocity T5E1 gun had excellent penetration performance against concrete and when installed in a heavily armored chassis was expected to be extremely effective in reducing heavy fortifications.”
The Army finally settled on a ninety-five-ton design with twelve inches of frontal armor. Compare that to the Sherman, which weighed about thirty tons and was protected by around two inches of frontal armor. Even the feared King Tiger, which the Germans used in combat, only had about six inches of frontal armor.
The T28 was almost thirty-seven feet long from the rear to the tip of the gun, and about ten feet high. It carried a crew of four and the 105-millimeter gun. But for close-range defense against infantry, the T28 only had a .50-caliber machine gun mounted on the roof, which required the vehicle commander to expose himself to fire it.
