The U.S. Army infantry manual at the start of the war was Hardee’s 1855 Rifle and Light Infantry Tactics.  Like most manuals, somebody condensed and made a paperback pocket version of Hardee’s. This particular version was published in large numbers, by at least two printers, and had several editions. This is a copy of the first printing from 1861. It was inexpensive and marketed not only as a quick pocket reference for officers, but as a study guide for enlistedmen. And it has a real cool cover.

This reproduction contains 128 pages of scanned original text, digitally cleaned to remove 165 years of age, formatted into folded signatures exactly like the original, hand stitched, and a heavy paper wrapper glued on. It’s a real good facsimile of the original.
 
These will be mailed to you so make sure to include your address!  Ignore the automatic "Event Delivery" reference at checkout.