Statistics for occurrence #1 of “South Mountain” in page 166 of The Photographic History of The Civil War: in ten volumes, Thousands of Scenes Photographed 1861-65, with Text by many Special Authorities, Volume 10: The Armies and the Leaders.:

...uly, 1862. He captured Roanoke Island and occupied New Berne. From these troops and others was organized, July 22, 1862, the Ninth Corps, with Burnside at its head. He served under McClellan at South Mountain , and at Antietam, where he commanded the left wing, and succeeded him in the command of the Army of the Potomac. Later, Major-General Burnside was assigned to command of the Department of the Ohio....
Max. Freq. Min. Freq.
Entity Corpus Doc Corpus Doc  
South Mountain (Pennsylvania, United States) 79 0 1 0 0 user votes
South Mountain (Arizona, United States) 0 0 0 0 0 user votes
South Mountain (Arizona, United States) 0 0 0 0 0 user votes
South Mountain (Arizona, United States) 0 0 0 0 0 user votes
South Mountain (Arkansas, United States) 0 0 0 0 0 user votes
South Mountain (Arkansas, United States) 0 0 0 0 0 user votes
South Mountain (Arkansas, United States) 0 0 0 0 0 user votes
South Mountain (California, United States) 0 0 0 0 0 user votes
South Mountain (California, United States) 0 0 0 0 0 user votes
South Mountain (Colorado, United States) 0 0 0 0 0 user votes
South Mountain (Colorado, United States) 0 0 0 0 0 user votes
South Mountain (Connecticut, United States) 0 0 0 0 0 user votes
South Mountain (Idaho, United States) 0 0 0 0 0 user votes
South Mountain (Idaho, United States) 0 0 0 0 0 user votes
South Mountain (Maine, United States) 0 0 0 0 0 user votes
South Mountain (Maine, United States) 0 0 0 0 0 user votes
South Mountain (Maine, United States) 0 0 0 0 0 user votes
South Mountain (Massachusetts, United States) 0 0 0 0 0 user votes
South Mountain (Massachusetts, United States) 0 0 0 0 0 user votes
South Mountain (Massachusetts, United States) 0 0 0 0 0 user votes
South Mountain (New Hampshire, United States) 0 0 0 0 0 user votes
South Mountain (New Hampshire, United States) 0 0 0 0 0 user votes
South Mountain (New Mexico, United States) 0 0 0 0 0 user votes
South Mountain (New York, United States) 0 0 0 0 0 user votes
South Mountain (New York, United States) 0 0 0 0 0 user votes
South Mountain (New York, United States) 0 0 0 0 0 user votes
South Mountain (New York, United States) 0 0 0 0 0 user votes
South Mountain (New York, United States) 0 0 0 0 0 user votes
South Mountain (New York, United States) 0 0 0 0 0 user votes
South Mountain (New York, United States) 0 0 0 0 0 user votes
South Mountain (North Carolina, United States) 0 0 0 0 0 user votes
South Mountain (North Carolina, United States) 0 0 0 0 0 user votes
South Mountain (Oregon, United States) 0 0 0 0 0 user votes
South Mountain (Oregon, United States) 0 0 0 0 0 user votes
South Mountain (Pennsylvania, United States) 0 0 0 0 0 user votes
South Mountain (Pennsylvania, United States) 0 0 0 0 0 user votes
South Mountain (Pennsylvania, United States) 0 0 0 0 0 user votes
South Mountain (Texas, United States) 0 0 0 0 0 user votes
South Mountain (Texas, United States) 0 0 0 0 0 user votes
South Mountain (United States) 0 0 0 0 0 user votes
South Mountain (United States) 0 0 0 0 0 user votes
South Mountain (Utah, United States) 0 0 0 0 0 user votes
South Mountain (Utah, United States) 0 0 0 0 0 user votes
South Mountain (Utah, United States) 0 0 0 0 0 user votes
South Mountain (Utah, United States) 0 0 0 0 0 user votes
South Mountain (Utah, United States) 0 0 0 0 0 user votes
South Mountain (Utah, United States) 0 0 0 0 0 user votes
South Mountain (Vermont, United States) 0 0 0 0 0 user votes
South Mountain (Vermont, United States) 0 0 0 0 0 user votes
South Mountain (Washington, United States) 0 0 0 0 0 user votes
South Mountain (Wyoming, United States) 0 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.