Statistics for occurrence #1 of “Potomac River” in chapter 4 of Admiral David D. Porter, The Naval History of the Civil War.:

... Potomac River
Conjectures and uncertainties. Secessionists and the Potomac. Secessionists erect batteries in sight of the capital...
Max. Freq. Min. Freq.
Entity Corpus Doc Corpus Doc  
Potomac River (United States) 286 12 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.