For starters, you need to study Volume 5 of the Official Records. Here are a couple of reports from 1861.

George Martin

O.R.-- SERIES I--VOLUME 5

DECEMBER 13, 1861.--Engagement at Camp Alleghany, West Virginia.
No. 6. -- Report of Lieut. Col. Z. T. Conner, Twelfth Georgia Infantry.
Beginning on p. 465

CAMP ALLEGHANY, December 17, 1861.

SIR: I have the honor of submitting this brief and hastily.drawn.up report of the battle of 13th instant:
About 4.30 o'clock in the morning, in obedience to your orders, I proceeded with seven companies of the Twelfth Georgia Regiment to occupy the rude and hastily-drawn-up intrenchments. At 6.30 the enemy were reported in strength upon our right flank, and about sunrise the firing commenced, and was continued without intermission for over two hours, the enemy from their greatly-superior force disputing most obstinately every inch of ground. The contest was so closely waged for some time that I was induced to dispatch two companies from Twelfth Georgia Regiment, Company B, Captain Hardeman, and Company I, the lamented Lieutenant Moore. commanding, to re-enforce our little band and aid in driving the enemy back.

About this time the attack was commenced upon our left, the enemy having covered himself by the heavily fallen timber until within 50 paces of our temporary earthworks. The firing had little effect except in exposed positions, which resulted in some deeply-to-be-deplored casualties. The death of those gallant officers, Captain Anderson and Lieutenant Reger, and badly wounding that most efficient, indefatigable, and brave officer Captain Deshler, who, though shot down, utterly refused to be sent from the field until the enemy were repulsed with great loss.
The conduct of the officers and men of the entire left wing was exceedingly creditable. For list of casualties I beg leave to refer you to accompanying tabular statement of Lieutenant Whitesides, acting adjutant Twelfth Georgia Regiment.

I am, very respectfully, your obedient servant,
Z. T. CONNER,
Lieutenant-Colonel Twelfth Georgia Regiment.

Col. EDWARD JOHNSON,
Commanding Allegheny Line

..........

CAMP BARTOW, GREENBRIER RIVER, October 7, 1861.

COLONEL: In my note of the 3d instant I gave you a brief account of the attack made that day upon our position by the enemy. Advancing along the turnpike with a heavy column, composed of infantry, artillery, and cavalry numbering, at a safe estimate, from 6,000 to 7,000 men, he drove in our advance pickets at an early hour in the morning. About 7 o'clock he encountered the main body of the advance guard, re-en-forced to about 100 strong, and posted on the right side of the turnpike, 1 mile from our lines, by Col. Edward Johnson, of the Twelfth Georgia Regiment, who took command in person. You will find this position designated upon the accompanying map by the capital letter E.

It is but justice to this superior officer and to the gallant band whose movements he directed to say that it would not have been possible for so small a force to have been more skillfully handled, or to have exhibited more obstinate courage in the face of numbers so overwhelming. They held the column of the enemy in check for nearly an hour, pouring into the head of it a galling fire, not withdrawing until six pieces of artillery had opened briskly upon them, and full battalions of infantry were outflanking them on the right, and then retiring in such order and taking such advantage of the ground as to reach our camp with but trifling loss. To this brilliant skirmish, in which Colonel Johnson had his horse killed under him, is doubtless to be ascribed in a measure the exhilarated spirit manifested by our troops during the remainder of the day. Before taking leave of it and referring to former dispatches, I would beg once again to direct to Col. Edward Johnson the special attention of the commanding general, not simply for this peculiarly brilliant service, but for his gallant and efficient conduct throughout the entire engagement. So soon as it had become apparent that the enemy contemplated a systematic attack upon our camp, I disposed of my entire force to meet it. To convey a correct idea, not simply of that disposition, but of the subsequent action, I must pray reference to the accompanying map, for which I am indebted to Lieutenant-Colonel Barton, of the Third Arkansas Regiment.

As I have already reported to you, our position is not by nature a commanding one. The causes of its weakness are the necessity of defending extended lines on our front (not less than a mile) and on our flanks, and the fact that there are points in our rear which, in possession of an enemy, might give us great trouble. The works essential to our safety were in progress of construction at the time of the attack, but were only partially completed, nothing whatever having been done to strengthen our right flank or our rear.

I am happy to say that during the last three days, through the indefatigable efforts of Lieutenant-Colonel Barton, in immediate charge of the works, backed by the cheerful labor of the men, we are already in condition to defy an approach from any quarter. Not doubting that the attack upon us had been to some extent invited by our commencing to fortify ourselves against it, and fearing that the enemy might have been fully advised of our weak points until he had actually begun his retreat, my mind could not dispossess itself of the idea that he had sent another column over the mountains to turn our right flank. To prepare for this danger I held the First Georgia Regiment, so far as that could be done, in reserve for what I apprehended would be a desperate struggle. I also sent expresses to Colonel Baldwin, whom I had previously ordered to the top of the Alleghany Ridge, directing him to move the Fifty.second Virginia Regiment as rapidly down as possible, and to fall upon the rear of the enemy should he undertake to fa11 upon ours. That gallant regiment responded, as I have learned, most heartily to the call, and when halted upon the road by the tidings that the day had already been won, despite of its not-to-be-doubted patriotism, could not entirely conceal its chagrin.

The two brigades in this camp, weakened by the absence of the several corps on detached service, the Fifth having been reduced from this cause and from sickness to scarce one-third of its legitimate number, I posted in the following order: The First Georgia Regiment upon our extreme right, under command of Major Thompson, Colonel Ramsey, the field officer of the day, having been cut off from us by the enemy while discharging his duty upon the road; next to it was placed the Twelfth Georgia Regiment--both of these regiments designed for the immediate command of Colonel Johnson. At an early moment I threw out what few mounted men were available, under Captain Sterrett, of the Churchville Cavalry, to different points along the valley upon our right, for the purpose of bringing us timely notice of an approach by the enemy, and I also strengthened considerably the picket guards advanced in that direction. The center I intrusted to the Fifth Brigade, under command of Colonel Taliaferro, composed of the Forty-fourth Virginia Regiment, Colonel Scott; the Twenty-third Virginia Regiment, Lieutenant-Colonel Taliaferro, and Major Reger's battalion [Twenty-fifth Virginia], commanded in his absence from sickness by senior Captain John C. Higginbotham. This brigade was reduced in the course of the action by the detachment of 100 men, under Major Jones, of the Forty-fourth, to re-enforce our left wing. This detachment marched in gallant style under the enemy's fire to the position assigned it in line. The troops on this wing, which from the character of the ground were widely dispersed, fell under the general command of Colonel Rust, of the Third Arkansas Regiment, and consisted of his own command, the Thirty-first Virginia Volunteers, Lieutenant-Colonel Jackson, and the battalion of Lieutenant-Colonel Hansbrough, commanded in his absence on account of sickness by senior Capt. J. A. Robertson. Upon this flank also two field pieces had already been placed in battery, enfilading the Huntersville road, which runs at right angles, if, indeed, those terms can be applied to serpentine mountain roads, from the turnpike. These guns were under the immediate charge of Capt. P. B. Anderson, and the zeal, skill, and determination of that officer leave no doubt that they would have done great execution had the enemy ventured to call them into action. Captain Shumaker's battery, consisting of four pieces (6-pounders), one of them rifled, and one 6-pounder, under Captain Rice, was held in readiness for the front and right flank. The places occupied by these various corps you will find specified upon the map.

Our forces were all in position, when at about 8 o'clock the enemy opened a heavy fire from six pieces of different caliber, placed in a field upon the right-hand side (to them) of the turnpike road, and bearing upon our front and center. This number was subsequently increased by two other pieces placed on the opposite side of the turnpike, one near it and the other upon the rise of the hill. This fire (of round shot, spherical case, shell, and occasionally, upon our left wing, of canister) was continued with extraordinary rapidity and without intermission for upwards of four hours, the eight guns constituting the well-known field batteries of Howe and of Loomis.

The hill occupied by Colonel Taliaferro's brigade, invitingly exposed to all of these batteries, received the greater share of their attention, and but for the protection afforded by the ditch and embankment running along its brow, and constructed under the immediate supervision of Colonel Taliaferro himself, we should doubtless have had inflicted upon us a very severe loss indeed. This fire was returned with great energy and, as the result has proved, with signal effect by the guns of Captain Shumaker and Captain Rice and by one piece detached from Captain Anderson's battery and placed upon the hill occupied by Lieutenant-Colonel Jackson. Lieutenant Massie, its proper chief, being quite indisposed, although he maintained his position near his piece, it was placed under the command of Captain Deshler, aide-de-camp to Colonel Johnson.

From the fact that the rifled gun of Captain Shumaker soon became useless to us (for the cause of this great misfortune see his own report addressed to myself), at no time could we bring more than five pieces into action to return the fire of the enemy's eight. Yet that fire was returned, and that with so much spirit and energy, as to make this artillery duel, rendered peculiarly interesting by the character of the field and its mountain surroundings, ever memorable by those who beheld it. That the casualties among our cannoneers should have been so few is a subject of sincere congratulation, and is very much ascribable to the sound judgment of Captain Shumaker, who repeatedly changed the position of his guns when those of the enemy had obtained his range. For a minuter description of the action in this its most striking phase I take great pleasure in referring to the report of that consummately cool and skillful officer. From it you will learn why it was that our pieces, at the close of the four hours' interchange of fire, were temporarily withdrawn, inducing our friends upon our extreme left and evidently the enemy to suppose that they had been silenced.

At about 9.30 a strong column of infantry was seen to move towards our left flank. Having crossed the so-called river (in fact, a shallow stream of about 20 yards in width), near the point designated on the map by the capital letter A, it undertook to turn our position in that direction. Soon, however, it encountered a portion of the Third Arkansas Regiment, which drove it precipitately back with a destructive fire. The enemy subsequently turned two of his pieces upon this portion of our left wing, pouring out canister and shell in large volumes, but. fortunately, on account of the protection afforded by the woods, with but little execution. Simultaneously with this movement towards our left another column of infantry ascended the wooded hill before our right wing at the point designated upon the map by the capital letter B.(*) Having become at its head involved in a slight skirmish with one of our picket guards, it was immediately and strongly re-enforced. Subsequently to the repulse of the column from our left flank it proceeded in the same general direction, ascending the hill at the point designated by the letter C,(*) and swelling the force, which now began to threaten seriously our front and right, to some 4,000 men. They moved along the side of the hill, opening upon our lines a desultory fire of rifled musketry, which was continued until the close of the action. So soon as the designs of this column were fully developed I ordered the Twelfth Georgia Regiment to take position near the stream, where a small detachment of it, under Lieutenant Dawson, had already been posted, with instructions to engage the enemy whenever he should attempt to cross it.

From the fact that this movement was made in full face of largely-superior numbers, armed with a superior weapon, and protected by cover of the forest, it was made with an alacrity and a regularity which deserve high commendation, as does also the cool determination with which this command, protecting itself as best it might against enemy's fire: received it, but returned scarce a shot. Not long thereafter I ordered Captain Shumaker to open upon the same column, directing his fire to where he supposed the head of it to be. This he promptly did with two of his pieces, and so effectively, that in a short time the unmistakable evidence of their rout became apparent. Distinctly could their officers be heard, with words of mingled command, remonstrance, and entreaty, attempting to rally their battalions into line and to bring them to the charge; but they could not be induced to reform their broken ranks nor to emerge from the cover of the woods in the direction of our fire. Rapidly and in disorder they returned into the turnpike, and soon thereafter the entire force of the enemy--artillery, infantry, and cavalry--retreated in confusion along the road and adjacent fields, leaving behind them at different points numbers of their killed, guns, knapsacks, canteens, &c. Among other trophies taken were a stand of United States colors, which are held subject to the order of the commanding general.

This engagement lasted from 7 in the morning to 2.30 o'clock in the afternoon, at which time the enemy, who had come with artillery to bombard and demoralize us, with infantry to storm our camp, with cavalry to rout and destroy us, and with four days' cooked rations in his haversacks to prosecute a rapid march either toward Staunton or toward Huntersville, was in precipitate retreat back to his Cheat Mountain fastness; and it is certainly a matter not unworthy of mention that while his first insolent advances were received with defiant cheers, running from one end to the other of our line, he was permitted to take his departure under the simple reports of our pieces firing upon him so long as he continued within their range. The relative weakness of our force and the entire absence of cavalry prevented our pursuing him, and thereby realizing the legitimate fruits of our triumph.

His loss in killed and wounded is estimated at from 250 to 300, among them an officer of superior rank. Our own, I am happy to say, was very inconsiderable, not exceeding 50 in all. This most gratifying result is to be attributed in a great degree to the remarkable coolness of regimental and company officers, who never seemed for a moment to lose their presence of mind, never allowed their men unnecessarily to expose themselves, and profited by every advantage of ground and position to shield them from danger.

In conclusion, I take great pride in saying that the bearing of all the troops, both officers and men, with but few exceptions, was highly creditable to themselves and to the army. Among those who enjoyed the opportunity coveted by all of attracting special notice, in addition to the name of Colonel Johnson, I would mention those of Captain Shumaker, who was wounded at his battery, and to whom I have already had repeated occasion to refer; of Capt. William H. Rice, of whom Captain Shumaker speaks in the following emphatic language: "He had been working his piece beautifully for two hours, and too much praise cannot be given him for the deliberate manner with which he loaded and fired his piece, loading and firing by detail for an hour in the midst of a storm of shot and shell from the enemy," until he was stricken to the earth severely wounded; of Captain Deshler, who directed a rapid fire with marked effect, and of Sergeant Graves, who fell mortally wounded in the cool and gallant discharge of his duty. Peculiarly distinguished among the advance guard, where all were distinguished, must be recorded the names of Lieutenant Gibson, of the Third Arkansas Regiment, the officer in immediate command; of Private Slayton, of the Thirty-first Virginia Regiment, who was severely wounded, and of Private J. W. Brown, of Company F, First Georgia Regiment, who, upon hearing the order to fall back, exclaimed, "I will give them one more shot before I leave," and while ramming down his twenty-ninth cartridge fell dead at his post. Nor can I omit mention in this connection of Lieutenant-Colonel Barton, who, in the absence of engineer staff officers, designed and was in active prosecution of the works to which we are so much indebted for the defense of our position, and who has shown himself at all times prompt to render cheerful and efficient service.

It is hardly necessary to add that Colonel Taliaferro, whose marked coolness and energy could not fail to inspire his men, and Colonel Rust, in command of the left wing, from which the enemy was first repelled, discharged their responsible duty successfully and well. Finally, my own thanks are specially due to my aides, Maj. F. S. Bloom and Lieut. W. D. Humphries, C. S. Army, for the gallant and efficient manner in which they responded to the peculiar and exposing calls made upon them. It is but justice to add that Cadet Henry Jackson, C. S. Army, drew notice to himself by his gallantry under fire.

I have the honor to inclose herewith a list of casualties.

I am, sir, very respectfully, your obedient servant,
H. R. JACKSON,
Brigadier-General, Commanding.

Col. C. L. STEVENSON,
Adjutant General, N. W. A.
pp. 224 -229

[Inclosures. ]
List of casualties at the battle of Greenbrier River, October 3, 1861.
O Officers.
M Enlisted Men. A Aggregate

--Killed-- -Wounded- Missing.
Command. O M O M O M A
Third Arkansas .... 2 .... 9 .... 4 15
First Georgia .... 1 .... 1 .... .... 2
Twelfth Georgia .... 1 .... 4 .... .... 5
Twenty-third Virginia .... .... .... 2 .... .... 2
Thirty-first Virginia .... 1 1 2 .... 9 13
Forty-fourth Virginia. .... .... 1 4 .... .... 5
Rice's battery .... 1 1 4 .... .... 6
Shumaker's battery .... .... 1 3 .... .... 4
Total .... 6 4 29 .... 13 52
[bitmap]

O.R.-- SERIES I--VOLUME 5 [S# 5]
DECEMBER 13, 1861.--Engagement at Camp Alleghany, West Virginia.

No. 10. -- Return of casualties in Colonel Edward Johnson's command in the engagement at Camp Alleghany, December 13, 1861.(*)
Page 468

O Officers. A Aggregate
M Enlisted Men.

--Killed-- -Wounded- Missing.
Command. O M O M O M A
Brigade staff. ..... .... 2 .... .... .... 2
Twelfth Georgia 1 5 1 36 .... 4 47
Twenty-fifth Virginia 1 1 .... 11 .... 5 18
Thirty-first Virginia 1 5 4 27 .... .... 37
Fifty-second Virginia .... .... .... 2 .... 6 8
Hansbrough’s battalion 1 3 1 10 .... 13 28
Lee Battery 1 .... .... .... .... .... 1
Miller’s battery .... 1 1 3 .... .... 5
Total 5 15 9 89 .... 28 146

BUFFALO MOUNTAIN, WEST VIRGINIA
13 December 1861
or
Camp Allegheny
Allegheny Summit

OR- Series I, Volume V, Chapter XIV, Pg 456
[http://www.fortunecity.com/victorian/pottery/1080/buffalo_mountain_wva_13dec61.htm]

Confederate Forces
COLONEL EDWARD JOHNSON

12th Georgia Infantry Regiment --- Lieutenant Colonel Z. T. Connor

Company B – Captain Isaac Hardeman

Company I – Lieutenant H. C. Moore

(remaining Companies unknown)

1 Battalion, 25th Virginia Infantry --- Major A. G. Reger

Lee Rifles – Captain R. D. Lilly

Rockbridge Guards – Lieutenant J. J. Whitmore

Detachment, Franklin Guards – Sergeant E. W. Boggs

Detachment, Upshur Greys

31st Virginia Infantry Regiment --- Major F. M. Boykin

Hansborough's Battalion --- Lieutenant Colonel Hansborough (w)

Reger’s Battalion --- Major A. G. Reger

52nd Virginia Infantry Regiment --- Major Ross

Detachment, Pittsylvania Cavalry --- Lieutenant C. E. Dabney

Miller's Battery --- Captain Miller
2 Sections, Lee Battery --- Captain P. B. Anderson (k)

STRENGTH= Approximately 1,200
CASUALTIES= Killed- 20, Wouneded- 96, Missing- 28

Partial Casualty List

Moore, Lieutenant - Mortally Wounded

Henry E. Moore
Residence Lowndes County GA;
Enlisted on 6/14/1861 as a 1st Lieutenant.
On 6/14/1861 he was commissioned into "I" Co. GA 12th Infantry
He was Killed on 12/13/1861 at Alleghany, VA

.............
Here are two men who died at Camp Alleghany, found in the roster of the regiment in the American Civil Research Database. I have not made a further search of the regiment.

William H. Robinett

Residence Marion County GA;
Enlisted on 6/15/1861 as a Corporal.
On 6/15/1861 he mustered into "K" Co. GA 12th Infantry
He died of disease on 8/16/1861 at Camp Alleghany, VA
(Died, fever)

George W. Rodgers

Residence Calhoun County GA;
Enlisted on 6/10/1861 as a Private.
On 6/10/1861 he mustered into "D" Co. GA 12th Infantry
He died of disease on 8/26/1861 at Camp Alleghany, VA
(Last name: Rogers)