By the winter of 1861, it was apparent that the Southern armies needed more men. The enlistment of most of the first volunteers expired in the Spring of 1862 and it was clear that the war was not going to be short or easily won. In February, 1862, each of the Confederate States received requisitions for more troops. Georgia was asked for twelve regiments. Since the state was divided into military districts, all men between 18 and 45 were ordered to report to the parade ground of their respective districts on March 4th where they were to volunteer. The governor, Joseph E. Brown, indicated that if not enough volunteers stepped forward he would draft what he needed.

Most companies of the 43^rd Georgia were formed on either March 4th or 10^th in their respective counties and then traveled by wagon or rail to Camp McDonald for organization and training. Camp McDonald was the largest of the three training camps and the destination of men from forty-three counties, about half of the new recruits. It was located seven miles north of Big Shanty (just above Marietta), a railroad depot on the railway that ran from Atlanta to Chattanooga.

The soldiers of the 43^rd Georgia came from six counties that lie North of Atlanta: Cherokee, Pickens, Forsyth, Hall, Jackson, and Banks. There were enough troops at McDonald to form six new regiments which were designated the 39^th, 40^th, 41^st, 42^nd, 43^rd, and 52^nd as well as a new battalion, the 9^th . Over the course of the war, most of these regiments would serve together in the same brigade.

The 43^rd Regiment, Georgia Volunteers, Army of Tennessee, came into being on March 19, 1862. After about a month at Camp McDonald,where there were many fatalities due to disease, the regiment left for Chattanooga and the District of East Tennessee under the command of Maj. Gen. E. Kirby Smith. While in this command they participated in two engagements:

The 43rd marched into Kentucky with Kirby Smith but saw no action, just long grueling marches over several months in which they covered 700 miles. Going into Kentucky, one participant said the artillery had to be hauled over the mountain passes by hand and that it was the worst country they had ever seen. When they retreated in December, it was in the snow without much of their baggage. At least two companies put in requisitions for shoes with the justification that some of the men were barefooted.

Once back in Tennessee, the regiment was transferred along with some of her sister regiments to the Department of Mississippi and East Louisiana . They were now serving as a Georgia brigade under Brig. Gen. Seth Barton.  Lt. Gen. John C.Pemberton was in command of the Department.

Following his successes in West Tennessee, Maj. Gen. Ulysses Grant set his sights on Vicksburg. Given that the city was impregnable from the Mississippi, a land approached was needed. Grant initially tried to march south through Mississippi but a cavalry raid on his main supply base at Holly Springs forced him to retreat. A week later, Maj. Gen. William T. Sherman landed troops North of Vicksburg but was repulsed with heavy losses at Chickasaw Bayou. Grant then tried a number of schemes seeking to land a force south of the city. He eventually succeeded by marching his army south through Louisiana and ferrying them across at Bruinsburg. He then marched for the state capital, Jackson, which lies east of Vickburg, to destroy the railroad supplying Pemberton and disperse any reinforcements on their way to aid Pemberton's army. Along the way he fought several small battles against portions of Pemberton's and Lt.Gen. Joseph E. Johnston's armies.

On May 12th, Pemberton finally left Vicksburg with the general plan of moving southeast to cut Grants supply line. As Johnston learned of the deteriorating situation in Mississippi, he urged Pemberton to unite with him. After much indecision, Pemberton decided to reverse his army's line of march and rendezvous with Johnston but it was too late. Grant had learned of Pemberton's plans and sent his forces southwest to intercept.  Pemberton was caught by surprise, but was lucky in that he occupied a good defensive position, a high hill , named after the local land owner, Champion. As the battle progressed, it became apparent to the Federals that Pemberton's left flank was "up in the air" and troops were sent to the union right to out flank the Confederates. The Confederates responded by adjusting to the left resulting in a thinly streched line with gaps of up to several hundred yards between units. Barton's brigade was not in the opening battle due to its position in the original line of march, but as the left was threatened, the 40th, 41st, and 43rd Georgia regiments were ordered to save the left flank by moving 2000 yards at the double quick and attacking. They had initial success driving skirmishers back some 300 yards before grinding to a halt in the face of a large number of Union attackers. Bartons' brigade had, in fact, developed a salient, and as Federals pressed in on the left and on the right, Barton's men were in danger of being surrounded. In the end, they gave way with many casualties.

Prior to Baker's Creek, the regiment had been engaged in small unit actions and minor skirmishes. The fight at Baker's Creek was their most desperate and the battle in which they suffered the most casualties. Col. Skid Harris was wounded and died that evening. Baker's Creek has gone largely unnoticed for its significance until relatively recently although contemporary observers understood its importance. Baker's Creek was the primary field battle fought by Grant against Pemberton before compelling Pemberton to retreat into Vicksburg and the subsequent siege. The loss at Baker's Creek doomed Vicksburg which, in turn, doomed the Confederacy.

The 43rd was so decimated at Baker's Creek they were placed in the southern most part of the Vicksburg line where little action was expected. One account says a number of them served as gun crew for "Whistling Dick", a large siege gun (would like to verify this). The fall of Vicksburg on July 4th, 1863 was strategic because it allowed the Federals total control of the Mississippi river cutting off Texas, Louisiana, and Arkansas from the rest of the South and preventing supplies from flowing East. Vicksburg surrendered as Lee lost at Gettysburg. The high-water mark of the Confederacy had been reached in both the west and east. When Vicksburg surrendered, the 43^rd was paroled and in September returned to Chattanooga.

After Chattanooga, the 43rd was in the brigade of Brig. Gen. Macellus A. Stovall and was in most of the actions of the Atlanta campaign.

After Jonesboro, they marched into Tennessee, then to South Carolina, finally joining the remnants of Robert E. Lee's army.

By April, 1865, there were so few left in the 40^th, 41^st, and 43^rd that the three regiments were consolidated into the 40^th Georgia Battalion of Henderson's Brigade which surrendered as part of Lee's army at Greensboro, NC in 1865.