The M-26 was developed near the end of World War II and named after World War One General John J Pershing of the American Expeditionary Force. The M26 Pershing had a slow and arduous beginning, when the need for a heavy tank was not in the priorities of the US Army. Instead, efforts were relegated to production of M3 Stuart Light Tanks and M4 Sherman Medium Tanks. It was not until the debut of the German Panther and Tiger series of tanks on the battlefields of Europe that the need for a heavily-armed, and armored, weapons system came to bear.
Considerable effort was then made to develop a gun system capable of competing with the German counterparts. The result was the M26 Pershing armed with a 90mm main gun (nearly on par with the German '88') and heavily armored overall. It was the closest weapon that the Allies would field that was akin to the German Panther, in terms of firepower and crew survivability.
The M26 Pershing arrived too late to be of any effective use (overall) in the European Theater, but a few (roughly 200) saw service with the 3rd and 9th Armored Divisions. At least 100 were kept in reserve as well.
The mammoth M26 Pershings would be part of the armored column that would cross the Remagen Bridge over the Rhine River and into Germany with the 9th Armored. About 20 M26s were reported to have seen any action at all. Ten M26s were also shipped out to the Pacific Theater for action in Okinawa, though arriving too late to be of any effective tactical use.
This was not the end of the line for the M26, however, as a total of 309 M26 Pershings were rushed to Korea in 1950 to provide extra firepower to counter the T-34/85s. A 1954 survey concluded that there were in all 119 tank vs. tank actions involving U.S. Army and Marine units during the Korean War, with 97 T-34-85 tanks knocked out and another 18 probable.
9th AD M-26 Pershing Heavy Tank photographed near Vettweiss, Germany in March 1945
The M4A3E8 was involved in 50% of the tank actions, the M26 in 32%, and the M46 in 10%. The M26/M46 proved to be an overmatch for the T-34-85 as its 90 mm HVAP round could punch all the way through the T-34 from the front glacis armor to the back, whereas the T-34-85 had difficulty penetrating the armor of the M26/46. The M4A3E8, firing 76 mm HVAP rounds which were widely available during the Korean War (unlike World War II), was equal to the T-34-85 as both tanks could destroy each other at normal combat ranges.
Although the M26 proved effective against the armour of the T-34/85s, the automotive deficiencies of the M26 in the mountainous Korean terrain became more of a liability, and so all M26s were withdrawn from Korea during 1951 and replaced with older up-gunned M4A3 Shermans and the newer M46 Pattons.
Post-war use saw a great number stationed throughout Europe with NATO through the Cold War, however, many were quickly replaced when the more reliable M46 Patton became available. Many alternative variants were devised, though some, like the self-propelled gun platform, not used by the US Army.
The M26 Pershing would later be reclassified as a Medium Tank and become the blueprint for tanks such as the M46, M47, M48 Patton, and M60 Main Battle Tanks. In 1948, the M26E2 version with a new more powerful and reliable engine and transmission became the M46 General Patton, which in turn was up-gunned and modified resulting in the M47 and eventually the M60 patton.