Herman Haupt Invents the Container Ship
Further digging at the LoC shows the image I posted earlier Saturday to be one of a series taken at Alexandria by Andrew Russell, documenting the U.S. Military Railroad. You can see more of them here. One in particular includes a caption explaining that “cars loaded at Alexandria can be carried on barges or arks to Aquia Creek, and sent to stations where the Army of the Potomac is supplied, without break of bulk.”
In other words, Herman Haupt invented the container ship.