The M26 Pershing was a US Army heavy/medium tank. It was briefly used in the final months of World War II during the Invasion of Germany and extensively during the Korean War. The T25 and T26 lines were developed in the midst of a heated internal debate within the U.S. Army in mid-1943 to early 1944 over the need for tanks with greater firepower and armor. A 90mm gun mounted in a massive new turret was installed in both series. The T26 series were given additional frontal hull armor. The T26E3 was the production version of the T26E1 with a number of minor modifications made as the result of field testing. In February 1945, the T-26 was fielded in the European theatre, where its performance received early praise from Army Ordinance officials. The Army named the tank after Army General John J. Pershing when it was re-designated the M26 in March.