2nd Brigade, 3rd Division, Center, XIV Corps, Army of the Cumberland, to January 1863.

As the Battle of Chickamauga began on the morning of 19 September, George Henry Thomas sent John Croxton's brigade to capture a Confederate brigade reported by Colonel Daniel McCook to be trapped on the west side of Chickamauga Creek.

With Croxton's brigade, the regiment fired engaged the 10th Confederate Cavalry of Henry Davidson's brigade, who were scouting the area, routing it before the Confederates came closer than rifle range.

The brigade then resumed the advance, being halted by the dismounted cavalry of Davidson's brigade in forested terrain at the base of a ridge west of Jay's Mill Road, where the opposing forces exchanged fire.

[3] When Claudius Wilson's Georgia Brigade, sent in to bolster the Confederate defense, attacked across the Brotherton road shortly after 09:00, they were spotted by Chapman, but his order for the right flank companies to retreat to face the Confederate advance was misunderstood as an order intended for the entire regiment, causing a general retreat.

However, Croxton prevented the Confederates from taking advantage of this by shifting the 10th Kentucky from the brigade left to the right.

After a volley from the 10th Kentucky stopped Wilson's advance, Chapman reformed the regiment on their right.

Due to exhaustion after having fought for two hours, Croxton's regiments retreated nevertheless, albeit slowly.

[4] They were relieved by Colonel John H. King's Regular brigade before 11:00 and went to the rear to draw ammunition, having exhausted their supply of 60 rounds per man in the fighting.

As Croxton could not see the entire brigade of six regiments, he delegated command of its right half to Chapman.

As the regiments came down the slope of the ridge, Chapman's horse was killed by a bullet, breaking its rider's arm in the fall.

[6] Croxton's brigade continued to advance toward the Winfrey Farm, running into John K. Jackson's Confederate brigade, which they engaged for thirty minutes before retreating due to exhaustion from five nearly uninterrupted hours of combat.

[7] On 20 September, the 10th and 74th Indiana repulsed the attack of John Brown's Tennessee Brigade in the Poe field.

After James Longstreet's attack routed much of Brannan's Division, Croxton's brigade changed front, with the 10th and 74th Indiana taking position on the left of Battery C, 1st Ohio Light Artillery.

While the latter fled into the Dyer Field, 10th Indiana Lieutenant Colonel Marsh Taylor led his regiment and the 74th in an orderly retreat back to the lines of John Reynolds' Division.

Passage of the Cumberland Mountains and Tennessee River and Chickamauga Campaign August 16-September 22.

Tunnel Hill, Buzzard's Roost Gap, and Rocky Raced Ridge, February 23–25.

Operations on Pumpkin Vine Creek and battles about Dallas, New Hope Church, and Allatoona Hills May 25-June 5.