Statistics for occurrence #1 of “Halleck” in chapter 7 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.:

...Johnson until May 28, 1868, except for a short interval during which he was suspended. There were four generals-in-chief of the armies: Brevet Lieutenant-General Scott, Major-Generals McClellan and Halleck , and Lieutenant-General Grant. The last named has been considered in previous pages of this volume, but the lives and services of the other three are summarized below, in addition to the treatment ...
Max. Freq. Min. Freq.
Entity Corpus Doc Corpus Doc  
† Henry Wager Halleck 533 18 15 4 0 user votes
H. W. Halleck 5,082 0 120 0 0 user votes
Halleck 1,974 0 538 0 0 user votes
Henry W. Halleck 1,400 0 40 0 0 user votes
Fitz-Greene Halleck 100 0 0 0 0 user votes
W. H. Halleck 94 0 4 0 0 user votes
Gen Halleck 34 0 0 0 0 user votes
Butler Halleck 27 0 1 0 0 user votes
M. G. Halleck 20 0 0 0 0 user votes
Joseph Halleck 9 0 3 0 0 user votes
Gens Halleck 8 0 0 0 0 user votes
A. J. Halleck 7 0 1 0 0 user votes
Benjamin Buel Halleck 6 0 0 0 0 user votes
Fitz-Green Halleck 4 0 0 0 0 user votes
Genenal Halleck 4 0 0 0 0 user votes
Isaac Halleck 4 0 0 0 0 user votes
W. Halleck 4 0 0 0 0 user votes
Charles Halleck 2 0 0 0 0 user votes
Ebenezer Halleck 2 0 0 0 0 user votes
George Halleck 2 0 0 0 0 user votes
Major-Gen Halleck 2 0 0 0 0 user votes
H. Wager Halleck 1 0 1 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.