Kidnapping plot issue that I've not considered

[L Verge]

The Soldiers' Home is so far north in D.C. that it is almost in Maryland (southern Montgomery County). I'm not very familiar with that area today with the growth and the Beltway interfering, but it might have been possible to exit the city without crossing a bridge. Actually, Ft. Stevens, where the Jubal Early raid on D.C. was thwarted, is just a few minutes from there. I don't think Jubal had to cross any river once he left the Monocacy behind outside of Frederick, MD.