GENERAL SHERMAN TANK

a World War II US Army tank weighing about 31 tons and carrying a 75-millimeter gun as its main armament. —SHSBC Binder 30 Approved Glossary

a World War II US Army tank weighing about thirty-one tons, named for William Tecumseh Sherman (1820-1891), US Civil War general and later commanding general of the United States Army. Used figuratively. And along about that way someplace, pulling on this string, you find the General Sherman tank, and that is simply somebody who is trying to stop things.