I am a practitioner or historical European martial arts (HEMA), and have been attempting to research the historical use of swords and bayonets in the USA, but so far lack the academic tools to do so; I have only found one manual online on the use of the saber from the early 20th century. I am interested primarily in fencing manuals from any point in US history (say, pre 1917), as well as historical accounts of hand to hand combat in 18th and 19th century America. Does anyone with a background in any of these periods either have any sources like this or any advice on where and how to look?
Matthew J. O'Rourke, a captain of volunteers on the Union side during the Civil War, published a treatise on the use of the saber in 1872, which was adopted as the Army's standard. You can get a free ebook of the manual here: https://play.google.com/store/books/details?id=M-ksAAAAYAAJ&rdid=book-M-ksAAAAYAAJ&rdot=1 The first half of the the book is "the Manual," regulations for how to draw a sword on parade, etc. The Part you're probably interested is the second half, "the Exercise," which contains the actual fencing. If you're familiar with other 19th century military sabre systems, say from the U.K., its fairly similar, but with a few differences.
There are few resources over on r/Hemascholar that might be in the area you're interested in, although the materials there tend to be eclectic. You might also ask over at r/wma.
Some resources from the US military side of things:
Matthew W. Berriman's The Militiaman's Manual: And Sword-play Without a Master : Rapier and Broad-Sword Exercises (1861)
William Gilham's Manual of Instruction for the Volunteers and Militia of the Confederate States (1861)
Philip St. George Cooke's Cavalry Tactics; Or Regulations for the Instruction, Formations, and Movements of the Cavalry (1864)
A. J. Corbesier's Principles of Squad Instruction for the Broadsword (1869) [PDF]
A. C. Cunningham's Sword and Bayonet (1906)
I thought I should add that Captain O'Rourke published a previous version of his work during the civil war itself.
Some more sources for 19th American military fencing:
Major Wayne, a former fencing instructor at West Point, published a manual intended for military use, unlike O'Rourke he includes a section on fencing with foils in preparation for a more "thrusty" weapon, as well as a broadsword or sabre section. https://books.google.com/books/about/The_Sword_Exercises_Arranged_for_Militar.html?id=zS8PAQAAMAAJ
The Militiaman's Manual (Full title: The Militiaman's Manual: And Sword-play Without a Master : Rapier and Broad-sword Exercises, Copiously Explained and Illustrated : Small-arm Light Infantry Drill of the United States Army : Infantry Manual of Percussion Musket : Company Drill of the United States Cavalry"), a work intended for Militia officers, contains fencing lessons for both thrusting and cutting weapons, perhaps intended, as the subtitle suggests, for people without access to a fencing master. The book sandwiches fencing instruction in with drill and the manual of arms for percussion musket, basically everything a militia officer would need to know. https://books.google.com/books/about/The_Militiaman_s_Manual.html?id=3moDAAAAYAAJ