The Heavy Tank M26 Pershing was an American heavy tank briefly used in World War II and in the Korean War. It was named after General John J. Pershing, who led the American Expeditionary Force in Europe in World War I.
Development of the M26 during World War II was prolonged by a number of factors, the most important being opposition to the tank from Army Ground Forces (AGF). As a result, only the initial 20 M26 (T26E3) tanks deployed to Europe in January 1945 saw combat in World War II. The M26 and its improved derivative, the M46 Patton, both saw more combat in Korea. The M26 was underpowered and mechanically unreliable and so was withdrawn from Korea in 1951, in favor of the M46, which had a more powerful engine. The lineage of the M26 continued with the M47 Patton, and was reflected in the new designs of the later M48 Patton and M60 Combat Tank.
The M26 was the culmination of a series of tank prototypes which began with the T20 in 1942 and represented a significant design departure from the previous line of U.S. Army tanks that had ended with the M4 Sherman. A number of design features were tested in the various prototypes, some of which were experimental dead-ends, but many of which would become permanent characteristics of subsequent modern U.S. Army tanks. The prototype series began as a medium tank upgrade of the M4 Sherman and ended as the U.S. Army's first operational heavy tank.