Mr. Miller,
Two items appear in the 6 December 1861 issue of the "Rockingham Register & Virginia Advertiser" newspaper (Harrisonburg, Rockingham Co., VA), Volume 40, No. 7.
The first item (page 1, column 5) is a copy of an article which ran in the "Winchester Virginian" newspaper on 26 November 1861. This article noted: "The sentence of the Court Martial was to-day, at a few minutes before 1 o'clock, carried into effect on the person of James A. Miller, for shooting, in September, last the Captain of his Company, John Henderson, of the Jefferson county cavalry." The article went on to describe in some detail the execution. This article concluded "Without a provocation he shot a ball thro' his Captain, and only by a miracle, as it were, has Capt. H. survived. Drunkenness was the only plea, in extenuation; but he was only one or two degrees in liquor at the time he committed the offence--excited, but not drunk, in the general acceptation of the term."
The second item (page 1, column 3) is a letter headed "Camp Maupin, Head Quarters, Nov. 27th, 1861" and signed by "O.P.H.". My research has identifed this man as O. P. Horn, Major, 58th Virginia Militia. In his letter, Major Horn wrote "I witnessed, on yesterday, one of the most painful sights I ever beheld, and one I hope I may never be called upon to witness again--the execution of James Miller, according to the mode of war, by being shot, for shooting his Captain." Major Horn went on to describe some family background concerning Miller. Horn continued "The circumstances of the difficulty between Capt. Henderson and private Miller were owing to a misunderstanding in regard to mustering into service." The Major wrote "Mr. Miller was arrested and brought to this place [Winchester] for trial. He was tried by a Court Martial; and, according to military law, condemned to be shot. The execution took place on yesterday at half past 12 o'clock." Major Horn proceeded to describe the exeuction in detail, and wrote that "His lifeless remains were sent to his family, in Jefferson county, to-day." Major Horn concluded his description of the event -- "This should be a lasting warning to all fractious and disobedient men. But I am fearful the same scene will soon be enacted again, upon some who have deserted, or are staying home, disregarding the calls made upon them by those in authority. The military law is strict and severe, knowing no mercy to disobedience."

I have obviously serverely edited both items. If you are, or anyone is, interested in receiving a copy of the two noted items please send a SASE, containing an additional stamp to cover copy costs, to 199 Towers Rd., Mt. Solon, VA 22843. You will receive four pages containing the two items.

I hope this information has answered some of your questions.

Respectfully,
John P. Mann IV