The M-26 Pershing was the U.S. Army's first operational heavy tank, though it was later reclassified as a medium tank. It began as an up-armored version of the then-operational M4 Sherman, but the design process eventually produced a dramatically different tank with a much larger main cannon and heavier front armor than the M4 could support.
The M-26 was developed late in World War II and saw very little combat. Some of the approximately 2,200 M-26 Pershings that were built deployed with Patton's army against Remagen during the Battle of the Bulge, and a small number of the tanks were deployed to Okinawa shortly before the end of hostilities. During the Korean War, the M-26 proved to be underpowered and unreliable in the rough terrain of the Korean peninsula, which led to its rapid retirement and replacement by the M-47 heavy tank.
The M-26 Pershing was just under 21 feet long and weighed 46 tons. Most operational units mounted a .90-caliber main gun and two secondary machine guns. The tank was driven by an 8-cylinder engine that delivered up to 500 horsepower and could drive it at a maximum speed of 25 mph over an operational range of 100 miles.