Statistics for occurrence #1 of “McClernand” in page 526 of Robert Underwood Johnson, Clarence Clough Buell, Battles and Leaders of the Civil War: The Opening Battles. Volume 1.:

... The next of Grant's commands to advance was McClernand's. The orders to that effect have already been cited, and their execution is explained by Colonel Marsh, into whose brigade what was present of McClernand 's division seems to have merged. He says:
...
Max. Freq. Min. Freq.
Entity Corpus Doc Corpus Doc  
† John A. McClernand 2,049 278 51 4 0 user votes
McClernand 941 0 155 0 0 user votes
J. A. McClernand 348 0 6 0 0 user votes
Jonathan A. McClernand 108 0 0 0 0 user votes
John Alexander McClernand 40 0 6 0 0 user votes
Generals McClernand 20 0 0 0 0 user votes
Geas McClernand 6 0 0 0 0 user votes
Gen McClernand 4 0 0 0 0 user votes
John McClernand 2 0 2 0 0 user votes
Gen John A. McClernand 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.