Statistics for occurrence #1 of “Zzz” in chapter 91, page 510 of The Atlanta (Georgia) Campaign: May 1 - September 8, 1864., Part I: General Report.:

...sistant Adjutant-General, Fourteenth Army Corps: Captain: The following is a corrected report of the casualties in this division, as given by the brigade commanders in yesterday's operations: Zzz Jef. C. Davis, Brigadier-General, Commanding Division.
...
Max. Freq. Min. Freq.
Entity Corpus Doc Corpus Doc  
† ZZZ 3,532 210 0 0 0 user votes
Interrogavi Terramn Zzz 4 0 0 0 0 user votes
March Zzz 2 0 0 0 0 user votes
S. ZZZ 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.