Tennessee

Soldiers named the war's biggest killer after the hurried walk it forced on them.

Camp sanitation made bowel disease more lethal than combat in the Civil War, and soldiers gave it a set of regional joke names: the Tennessee quick step, the Tennessee trot, the Virginia quickstep, and plainly the flux. The quickstep was a real marching step of about 110 paces a minute, which is the point of the joke. The term is now obsolete outside Civil War writing.