We were not fighters like them; we were cunning and cowardly, and it was because of our cunning and cowardice, and our inordinate capacity for fear, that we survived in that frightfully hostile environment of the Younger World.
Union Pacific's 4-6-6-4 Challenger steam locomotive #3985 is the largest operating locomotive in the world. Built in July 1943 and still used by UP for occasional excursion throughout the western United States, the 3985 weighs 1,073,900 pounds (537 tons).
Readers might wish to consult David Fry's Danger Ahead! -- Historic Railway Accidents (UK website) [ GPL ]. The first self-propelling steam engine or steam locomotive made its outing on 13 February 1804 at the Pen-y-Darren ironworks. The machine was designed by Richard Trevithick. The engine was able to pull a load of 15 tons at a speed of about 5 mph. However, adhesion was a problem (iron wheels on iron rails = slipping).