Statistics for occurrence #1 of “Fort Henry” in chapter 2, page 19 of William Boynton, Sherman's Historical Raid:
... Grant and Commodore Foote, Halleck replied:
headquarters Department of the Missouri, St. Louis, January 29, 1862. Brigadier-General Grant, Cairo.
Make your preparations to take and hold Fort Henry .
I will send you written instructions by mail. H. W. Halleck, Major-General
...