The regiment was part of the Ohio Volunteer Infantry and played a significant role in several key battles and campaigns throughout the war.

It rendezvoused at Camp Taylor outside Cleveland, Ohio, and mustered in for three years service on January 1, 1863,[4][5][1] under the command of Colonel Oliver Hazard Payne.

In the aftermath of Maj. Gen Rosecrans' victory at the Battle of Stones River at the new year, the area was rife with Confederate regular and irregular forces, and their close proximity kept the 124th Ohio and the rest of the garrison strict in its picket discipline and alertness.

The men of the 124th and the rest of the garrison were commanded by Col. Charles Champion Gilbert who had been criticized for his slow action at the repulse of Gen. Braxton Bragg's invasion of Kentucky at Perryville despite checking the last rebel attacks and successfully counterattacking.

[10] Reports of Confederate activity further southwest near Columbia, led Gilbert to order Col. John Coburn to plan a reconnaissance in force there.

[note 1] Four (4 mi (6.44 km)) miles short of Spring Hill, Coburn made contact on his right with, a Confederate Army force composed of two regiments who were driven back.

The 124th's bold front it presented to the enemy enabled the ammunition train and artillery to get safely off the field and back to the fortifications at Franklin.

[5] The regiment saw no further combat during their stay at Franklin but suffered severely from disease endemic to the volunteer army of the time.

[13] As part of the Tullahoma Campaign, on Monday, their new brigade marched up into the mountains via Bradyville, TN while Rosecrans seized Hoover's Gap[note 3] to the south.

The 124th Ohio enjoyed the lull in the hot summer of 1863 at Manchester in a camp "of great beauty ... praised for its neatness and cleanliness.

"[13] Supplementing issued rations, the Ohio men "fared sumptuously off the luxuries of Corn and fruit afforded by the farms and orchards arouud them.

[note 4] (August 21 – September 8, 1863) Rosecrans did not immediately pursue Bragg and instead paused to regroup and study the difficult choices of pursuit into mountainous regions.

In mid-August, he would resume campaigning to take Chattanooga, Tennessee, and in the second week, the 124th Ohio received word to get ready to march.

[21] Due to the successful use of mounted infantry, specifically Col. John T. Wilder's brigade,[22][23] Rosecrans devised a deception to distract Bragg above Chattanooga while the army crossed downstream.

The Poe Branch of North Chickamauga Creek, [note 5] "a pure cold stream of water" ran through the town.

Minty' cavalry troopers and Wilder's men pounded on tubs and sawed boards, sending pieces of wood downstream, to make the Confederates think that rafts were being constructed for a crossing north of the city.

The deception worked and Bragg was convinced that the Union crossing would be above the city, in conjunction with Burnside's advancing Army of the Ohio from Knoxville.

[34] As Hazen's brigade stayed in the valle, XX Corps crossed at Caperton's Ferry, 4 miles (6.4 km) from Stevenson on Saturday, August 29, building a 1,250 feet (380 m) pontoon bridge there.

Virtually all of the Union army, other than elements of the Reserve Corps kept behind to guard the railroad, had safely crossed the river by September 4.

Johnston sent two weak divisions (about 9,000 men) from Mississippi under Maj. Gen. John C. Breckinridge and Maj. Gen. William H. T. Walker by September 4, and General Robert E. Lee dispatched a corps under Lt. Gen. James Longstreet from the Army of Northern Virginia.

[37][38] On Tuesday, Bragg, who had already decided to abandon the city (Rosecrans' goal) to withdraw to a more defensible position further south, learned from his cavalry that the three corps were across the river to the southwest.

[40] Believing Bragg was fleeing in chaos to Dalton or Rome, Georgia,[41] Rosecrans ordered his diversion force into the city.

Starting in four ranks, they got on very well until the deep and rapid portion of the river, when some of the short men became very apprehensive, leading the regiment to hold hands to keep from getting swept away by the current downstream.

Friday, September 11, the brigade marched southeast through Lookout Mountain in the direction of Ringgold, GA. En route, as a rule, the men noted the local white residents had abandoned their homes and farms.

With rebels at Ringgold on Friday and at Davis's Cross Roads on Saturday, Rosecrans realized that he had narrowly escaped a trap, and he abandoned his pursuit and began to concentrate his scattered forces.

[47] As the 124th were with Hazen, on Saturday, September 12, he ordered McCook and the cavalry come back to Stevens Gap to join Thomas, intending for this combined force to continue up Lafayette Road to link up with Crittenden.

Unbeknownst to them, Forrest's cavalry had reported their movement, and Bragg, seeing saw an offensive opportunity, ordered Lt. Gen. Leonidas Polk to attack Crittenden's lead division, under Brig.