The brigade formed on or about June 15, 1862, and was composed of the following regiments:
- 14th Georgia Regiment, Col. Felix M. Price
- 35th Georgia Regiment, Col. Edward L. Thomas
- 45th Georgia Regiment, Col. Thomas Hardeman, Jr.
- 49th Georgia Regiment, Col. A. J. Lane
It was assigned to the Division of Maj. Gen. A. P. Hill. The first commander of the brigade was Brigadier Gen. Joseph R. Anderson of Virginia.
Under the command of Gen. Anderson, the brigade participated in the battles of Mechanicsville, fought June 26th, 1862; Gaines' Mill, June 27th, 1862; and Fraser's Farm, June 30th, 1862. Its effective strength when it crossed the Chickahominy on the afternoon of June 26th, was about 1750 men. In the series of bloody battles which delivered the Southern capitol from siege, this brigade lost 563 men in killed and wounded. Gen. Anderson resigned around July 20, 1862, and command of the brigade was handed over to Col. Edward L. Thomas, who had commanded the 35th Georgia Regiment with great success and gallantry in the above mentioned battles, as well as the Battle of Seven Pines.
As Hill's Division was assigned to the command of Gen. Thomas J. "Stonewall" Jackson on July 31, 1862, the brigade left the camp it had occupied since the battles around Richmond, and went to Gordonsville, where Jackson's forces had assembled. The brigade remained at Gordonsville until August 7, when it moved with the rest of Gen. Jackson's forces, by way of Orange Court House. On August 9, after a long and very hot march, Gen. Jackson's command encountered the enemyunder Maj. Gen. Pope, near Cedar Run in Culpepper, where he utterly defeated them, driving them several miles from the field of battle. Thomas' Brigade behaved with distinguishing gallantry in this battle, checking the advance of the enemy on the extreme right of Gen. Jackson's command, and holding them in check for some time, until after a long, obstinate, and bloody fight, the order was given by Gen. Jackson for a general charge, when the brigade advanced with the utmost bravery and enthusiasm, driving the enemy in utter rout before them. The loss of the brigade in this battle, known as the Battle of Cedar Run, was about 150 men killed and wounded. Among those killed was Lieut. Col. S. M. Manning of the 49th Georgia Regiment, one of the best and bravest officers in the brigade.
For some time after this battle, Thomas' Brigade, with the rest of Gen. Jackson's Corps, was encamped at Crenshaw's Farm in Orange Co. Leaving which, about August 23, it proceeded under Gen. Jackson on that celebrated flanking march, which by its successful accomplishment, placed the Corps of the immortal Stonewall in the rear of Pope's army. The astonishing boldness of this movement, the remarkable success and secrecy of its execution, the daring and obstinate bravery with which Jackson's Corps, alone and unsupported, confronted and beat off Pope's Army on August 28 and 29, are among the wonders of this war. No man except the hero who commanded that corps, could have kept men firm under circumstances so extraordinary. Thomas' Brigade was in reserve on August 28. On the 29th, it charged upon, and routed with considerable slaughter, a force of the enemy on the Manassas Gap railroad. The brigade held this position for the rest of the day. After a long and bloody fight of nine hours, during which repeated enemy charges were repulsed, the brigade was driven from its position by an overwhelming enemy force. They united with Pender's North Carolina Brigade, and with their assistance the enemy force was finally driven back.
On the evening of August 29, 1862, the corps of Lieut. Gen. James Longstreet arrived. The long agony of Jackson's Corps was over. Five brave divisions had come to their assistance, and with their arrival, renewed confidence was instilled into the soldiers of Jackson, who, though by no means intimidated by the immense odds against which they were contending, were perfectly confident that with the heroes of Longstreet, they could hurl from their front the legions of Abolitionism. The next morning the conflict was renewed and raged desperately deadly. Pope�s Army had been largely reinforced by the remains of McClellan�s Peninsula Army. On that day, August 30, the classic plains of Manassas were the scene of a long and bloody battle, and a most disastrous defeat on the part of the enemy, ending in their utter rout. Thomas� Brigade fought on that day, and was among the foremost in the pursuit of the enemy. The brigade subsequently took part in the action near Chantilly on September 1, in which the enemy were again defeated and routed.
General Robert E. Lee�s Army invaded Maryland in 1862. Thomas� Brigade, with the rest of A. P. Hill�s Division, crossed the Potomac River near Leesburg, VA on September 5, 1862, and reached Frederick, MD two days later. After a few days rest, the march was resumed. They recrossed the Potomac at Williamsport, and reached Harper�s Ferry, by way of Martinsburg, on September 14, and assisted in the capture of the entire Federal force at Harper�s Ferry, numbering 11,000 men. The brigade, having been ordered to remain in Harper�s Ferry, did not participate in the Battle of Sharpsburg. It took part, however, in the subsequent encounter at Shepherdstown. A force of the enemy had crossed the Potomac there, and Maj. Gen. A. P. Hill turned upon them with Thomas�, Gregg�s, and Pender�s brigades of his gallant Light Division, and the enemy was driven back in utter rout across the Potomac. For some time thereafter, the army lay quiet near Bunker Hill in the Valley of Virginia.
While here, Col. Felix M. Price resigned and Lieut. Col. Robert Folsom was promoted to Colonel of the 14th Georgia Regiment. Col. Thomas Hardeman also resigned, and Lieut. Col. Thomas J. Simmons was promoted to Colonel of the 45th Georgia Regiment. Col. A. J. Lane, too, resigned, and Maj. Jonathan Rivers was promoted to Colonel of the 49th Georgia Regiment. Col. Edward Lloyd Thomas was promoted to Brigadier General, to which rank he was recommended by Maj. Gen. A. P. Hill immediately after the battles around Richmond, but the commission was not conferred upon him until November 1, 1862, after he had repeatedly earned his wreath while commanding the brigade in several bloody battles.
About November 10, 1862, the brigade left the Valley of Virginia, crossed the Blue Ridge Mountains at Milom gap, and marched by way of Orange Court House to Fredericksburg. It remained encamped there until December 11, when Gen. Burnsides crossed the Rappahannock River with the Federal Army. The brigade took position near Hamilton�s Crossing, where, being second in line, it remained quiet until December 13, when the grand attack of the enemy took place. The troops in its front having been pushed back by a strong column of the enemy, Thomas� Brigade, in a well-directed and energetic charge, in turn drove back and utterly routed the enemy in its front. The brigade suffered heavy losses in this engagement. The next day, the Federal Army, badly beaten and demoralized, recrossed the Rappahannock.