Statistics for occurrence #1 of “Potomac river” in chapter 3.21 of Southern Historical Society Papers, Volume 3.:

...from that city to Richmond; for three days was hid in a swamp on the Eastern Shore of Maryland, sleeping at night in a potato hole or house dug in the ground, and finally, in the attempt to cross the Potomac river , was intercepted and shot at by some Yankees in a launch from a Federal gunboat. He however escaped and reached the Virginia shore in safety, losing all his baggage, and the boat in which he crosse...
Max. Freq. Min. Freq.
Entity Corpus Doc Corpus Doc  
Potomac River (United States) 286 0 0 0 0 user votes
Potomac River (Maryland, United States) 2 0 0 0 0 user votes
Potomac River (Maryland, United States) 2 0 0 0 0 user votes

† This entity has been selected by the automated classifier as the most likely match in this context. It may or may not be the correct match.