OK, all you lovers of steam and history, try this on.
In 1863, after the Union defeat at Chickamauga, the B&O (in association with other roads) organised the movement of XI and XII Corps, Army of the Potomac, from Virginia to Bridgeport, Alabama. The operation has been called “the accomplishment par excellence in Civil War logistics.”
The B&O-specific piece involved moving over 20,000 men, and much of their equipment, over 412 miles in five days.
Your mission, should you decide to accept it, is to calculate approximately how many cars and how many trains (e.g., a million trains of a thousand cars each) the B&O used to do the deed.