Statistics for occurrence #1 of “Tennallytown” in chapter 6 of The Photographic History of The Civil War: in ten volumes, Thousands of Scenes Photographed 1861-65, with Text by many Special Authorities, Volume 5: Forts and Artillery.:
...Seventh Street Road, were all simultaneously started.
All these works were on the crest of a somewhat irregular ridge overlooking the valley of Sligo Branch.
This carried the general project from Tennallytown , within two miles of the Potomac, around to the north and east of the capital to Anacostia Branch.
The line once established by the location of the larger forts, the process already employed ...
† 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.