A relative of mine was researching and found the following, but I cannot verify it personally:

Information received from Fredericksburg National Battlefield Park indicates the 16th Georgia Infantry, CSA, was formed in the summer of 1861 from recruits from Madison, Elbert, Gwinnet, Habersham, Jackson, and Hart counties in Georgia. They were called the Sallie Twiggs
Regiment on the Georgia State muster rolls. The regiment was mustered into the Confederate States Army (CSA) in Suffolk, Virginia in 1862 and designated the 16th Georgia. The regiment saw combat for the first time in the Seven Days' battles in the spring/early summer of 1862 during the Union's Peninsula Campaign trying to capture Richmond from the South through the tidewater. The 16th was initially in Brigadier General T.R.R. Cobb's Brigade, Major General Lafayette McLaw's Division of Lieutenant General James Longstreet's Wing of the Army of Northern Virginia. (General Robert E. Lee assumed command of the Army of Northern Virginia during these battles, after General Joseph E. Johnston was severely wounded).

The next major battle was the Second Battle of Manassas, or Bull Run as the Union called it, in the latter part of August 1862 (Bob Coolidge has been unable to find any record of the 16th Georgia participating in that battle, or of McLaw's Division being involved, but he is still researching this).

The Union forces were soundly defeated at both the peninsula and Second Manassas, so General Lee made his first move to take the war out of Virginia into the North. He moved his forces into Maryland, and McLaw's Division with the 16th Georgia Infantry, among others, was assigned, in coordination with troops of Stonewall Jackson's Corps, to take out Union forces in and around Harpers Ferry, West Virginia, to protect General Lee's route of march. Unfortunately, Major General George McClellan, USA, and over 100,000 troops of the Army of the Potomac were marching on a collision course at Antietam Creek near the town of Sharpsburg, Maryland. The battle of Antietam was the bloodiest of the war. McLaw's Division, arriving on the scene after the battle had begun, was sent in to block a Union breakthrough near the Dunker Church. It succeeded in stopping the attack, but suffered heavy casualties.

Outnumbered, and with many wounded, General Lee moved his army back across the Potomac River into Virginia. McClellan's Union Army was very weary and suffering even more casualties, did not pursue.

In late fall of 1862, the Union Army of the Potomac, now under command of Major General Ambrose Burnside, moved to capture Richmond from the North by way of Fredericksburg, Virginia, which is halfway between Washington and Richmond. Again the Union suffered a serious defeat at the hands of General Lee, and the 16th Georgia Infantry was there at that time.

In the spring of 1863, the new commander of the Union Army of the Potomac, Major General "Fighting Joe" Hooker, moved to the West of Fredericksburg and crossed the Rappahannock River near the small village of Chancellorsville. In a brilliant move General Lee split his forces and attacked Hooker from two directions forcing him to retreat. In a ferocious battle, McLaw's Division, including the 16th Georgia Infantry, broke the only major Union resistance near the Old Salem Church on Plank Road.

General Lee decided to once again invade the North. He met the Army of the Potomac under the command now of Major General George Gordon Meade, USA, in battle at a small college town in central Pennsylvania called Gettysburg. The 16th Georgia was there, but victory belonged to the Union forces this time. Once again the Union forces did not pursue General Lee, and he was able to get his Army of Northern Virginia back to Virginia.

The South was having a hard time in its campaigns in the West, and General Lee transferred Longstree's Corps to Tennessee, where they participated in the battle of Chickamauga near Chattanooga. The 16th Georgia Infantry did not participate in this battle, as they were stationed in Knoxville guarding the supply lines for the Confederate forces.

Transferring back to Virginia, the 16th Georgia fought in the battle of the Wilderness to the West of where they were so victorious during the battle of Chancellorsville. This time the new Union Commander, Lt. General Ulysses S. Grant, did not quit fighting when he was defeated. He kept plunging forward, always moving to the West in an attempt to get around General Lee's flank.

After the Wilderness battle, there was the Battle of Spotsylvania Courthouse where the Union forces were again defeated, but with their superior numbers and supplies, they kept on coming. Facing the inevitable, General Lee withdrew from the field and moved his forces South to Petersburg, Virginia, where he "dug-in" to protect Richmond from Grant's army. At this point, the 16th Georgia, now under Brigadier General Wofford, was transferred to Major General Jubal Early's Division in the Shenandoah Valley. They fought up and down the Valley against Major General Phillip Sheridan, USA. Of note, Early moved his division out of the Valley, into Pennsylvania, and threatened Washington, D.C. from the North, actually entering the outskirts of the District. Grant was forced to pull units out of the Army of the Potomac and rush them to Washington. This relieved the pressure on General Lee and he was able to pull out of the fortifications and move to the West seeking maneuvering room, but abandoning Richmond in the process.

Early's Division, along with the 16th Georgia, was with Lee when he surrendered at Appomattox Courthouse in April 1865.