Statistics for occurrence #1 of “Maryland” in chapter 1 of The Photographic History of The Civil War: in ten volumes, Thousands of Scenes Photographed 1861-65, with Text by many Special Authorities, Volume 4: The Cavalry:

...in December, 1862, and participated in the famous mud march, January, 1863, about the time this photograph was taken. The men had ample time for schooling and training in the Middle Department, in Maryland and the vicinity of Washington. They proved their efficiency in Stoneman's raid in April, 1863, and at Brandy Station and Warrenton. Later they accompanied Sheridan on his Richmond raid in May, 1...
Max. Freq. Min. Freq.
Entity Corpus Doc Corpus Doc  
Maryland (Maryland, United States) 18,573 20 3 0 0 user votes
Maryland (Illinois, United States) 0 0 0 0 0 user votes
Maryland (Liberia) 0 0 0 0 0 user votes
Maryland (Louisiana, United States) 0 0 0 0 0 user votes
Maryland (Louisiana, United States) 0 0 0 0 0 user votes
Maryland (Louisiana, United States) 0 0 0 0 0 user votes
Maryland (New Jersey, United States) 0 0 0 0 0 user votes
Maryland (New York, 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.