Digital facsimile of the second edition (1862) from the Hathi Trust at this link. Notably in 1862 this small work written for Union surgeons was reprinted in Richmond, Virginia for the use of Confederate surgeons. The Richmond publisher J. W. Randolph, published an informative note on the source of this edition on the verso of the title page. It reads:
"In view of the great want of some convenient work on Military Surgery, we present a valuable little Treatise recently published by Dr. S.D. Gross, of Philadelphia. The book trade between the two sections of the continent having been interrupted, it has rendered it impossible for Dr. Gs publishers to furnish the work to the Southern Public. We avail ourselves of the copy recently published in the Southern Medical and Surgical Journal, Augusta, Geo."
Digital facsimile of the Richmond edition from the Internet Archive at this link.