Patrick Cleburne decided that the Texans were, "a fine body of men out of which good soldiers are made", and accepted them into his division.
The consolidated 6th-10th-15th Texas was sent to Wartrace, Tennessee for training.
During the Battle of Chickamauga on 19–20 September 1863, the consolidated regiment was led by Colonel Roger Q. Mills and the brigade was led by Deshler.
Brigade losses were 52 killed and 366 wounded, a total of 418 casualties.
Deshler was killed, so Mills assumed command of the brigade and Lieutenant Colonel T. Scott Anderson took command of the 6th-10th-15th Texas.
The other units in the brigade were the 19th and 24th Consolidated Arkansas Infantry Regiment and the 17th-18th-24th-25th Consolidated Texas Cavalry Regiment (dismounted).

Deshler's brigade was ordered to advance at nightfall on the first day of Chickamauga.
The brigade's skirmish line, moving ahead of the battle line, stumbled into one of Richard W. Johnson's Union brigades in the dark woods and most of the skirmishers were captured.
In very confused fighting, Deshler's brigade drifted to the left of its intended track.
However, one of its regiments helped capture the colonel and 82 men of the 77th Pennsylvania Infantry Regiment.
Some of the captured skirmishers escaped in a highly fluid situation.
On the second day, Cleburne ordered Deshler's brigade forward to cover the retreat of two brigades that had been driven off.
As the brigade reached the crest of a rise, it was struck by a blast of Federal bullets.
Cleburne sent orders to Deshler to hold out as long as possible, so the soldiers dropped to the ground and returned fire.
For two hours and 30 minutes, Deshler's men held the line, but they suffered hundreds of casualties.
Deshler was struck in the chest by an artillery projectile and killed instantly.
At 2:00 pm Mills ordered most of the brigade to pull back 20 yd (18 m) and assigned a few sharpshooters to hold the crest.
At Chickamauga, the 15th Texas lost five killed, 16 wounded, and 14 captured or missing.

The 6th-10th-15th Texas fought with distinction at the Battle of Missionary Ridge on 24–25 November 1863.
The regiment formed part of a brigade under James Argyle Smith together with the 17th-18th-24th-25th Texas Cavalry (dismounted) and the 7th Texas Infantry Regiment.
Early on 24 November, William T. Sherman's Union troops crossed the Tennessee River and advanced toward the northern end of Missionary Ridge.
The commander of the Confederate Army of Tennessee, Braxton Bragg reacted slowly, but he finally ordered Cleburne to halt Sherman's forces.
In the late afternoon, Cleburne deployed Smith's brigade on Tunnel Hill just in time to block Union soldiers from occupying it.
Following some skirmishing, Sherman sent John M. Corse's brigade to attack Smith's Texans about 10:30 am on 25 November.
A brief counterattack threw the Union troops back, but Smith and Colonel Mills were seriously wounded and Hiram B. Granbury of the 7th Texas took command of the Texas brigade.
After Mills fell, Captain John R. Kennard assumed command of the 6th-10th-15th Texas.
Major Sanders was shot and had to have his right arm amputated.
The initial fighting was followed by uncoordinated and unsuccessful assaults by several Federal brigades.
Confederate reinforcements soon arrived, but, as related by another Southern soldier, the Texans were reluctant to give up their position in the front line because, "it was the first time they ever had a chance to fight the Yankees from behind breastworks and that they were rather enjoying it".
At 4:00 pm, Cleburne launched a major counterattack by striking the Federals' foothold with Alfred Cumming's brigade in front and the 6th-10th-15th Texas on the right flank.
The effort proved entirely successful and chased the Union troops off Tunnel Hill, capturing many prisoners.
The 15th Texas sustained losses of one killed, seven wounded, and two missing.

The 6th-10th-15th Texas fought at the Battle of Ringgold Gap on 27 November 1863.
Cleburne deployed Granbury's brigade just to the north of the gap.
Attacked by Charles R
Patrick Cleburne decided that the Texans were, "a fine body of men out of which good soldiers are made", and accepted them into his division. The consolidated 6th-10th-15th Texas was sent to Wartrace, Tennessee for training. During the Battle of Chickamauga on 19–20 September 1863, the consolidated regiment was led by Colonel Roger Q. Mills and the brigade was led by Deshler. Brigade losses were 52 killed and 366 wounded, a total of 418 casualties. Deshler was killed, so Mills assumed command of the brigade and Lieutenant Colonel T. Scott Anderson took command of the 6th-10th-15th Texas. The other units in the brigade were the 19th and 24th Consolidated Arkansas Infantry Regiment and the 17th-18th-24th-25th Consolidated Texas Cavalry Regiment (dismounted).
Deshler's brigade was ordered to advance at nightfall on the first day of Chickamauga. The brigade's skirmish line, moving ahead of the battle line, stumbled into one of Richard W. Johnson's Union brigades in the dark woods and most of the skirmishers were captured. In very confused fighting, Deshler's brigade drifted to the left of its intended track. However, one of its regiments helped capture the colonel and 82 men of the 77th Pennsylvania Infantry Regiment. Some of the captured skirmishers escaped in a highly fluid situation. On the second day, Cleburne ordered Deshler's brigade forward to cover the retreat of two brigades that had been driven off. As the brigade reached the crest of a rise, it was struck by a blast of Federal bullets. Cleburne sent orders to Deshler to hold out as long as possible, so the soldiers dropped to the ground and returned fire. For two hours and 30 minutes, Deshler's men held the line, but they suffered hundreds of casualties. Deshler was struck in the chest by an artillery projectile and killed instantly. At 2:00 pm Mills ordered most of the brigade to pull back 20 yd (18 m) and assigned a few sharpshooters to hold the crest. At Chickamauga, the 15th Texas lost five killed, 16 wounded, and 14 captured or missing.
The 6th-10th-15th Texas fought with distinction at the Battle of Missionary Ridge on 24–25 November 1863. The regiment formed part of a brigade under James Argyle Smith together with the 17th-18th-24th-25th Texas Cavalry (dismounted) and the 7th Texas Infantry Regiment. Early on 24 November, William T. Sherman's Union troops crossed the Tennessee River and advanced toward the northern end of Missionary Ridge. The commander of the Confederate Army of Tennessee, Braxton Bragg reacted slowly, but he finally ordered Cleburne to halt Sherman's forces. In the late afternoon, Cleburne deployed Smith's brigade on Tunnel Hill just in time to block Union soldiers from occupying it. Following some skirmishing, Sherman sent John M. Corse's brigade to attack Smith's Texans about 10:30 am on 25 November. A brief counterattack threw the Union troops back, but Smith and Colonel Mills were seriously wounded and Hiram B. Granbury of the 7th Texas took command of the Texas brigade. After Mills fell, Captain John R. Kennard assumed command of the 6th-10th-15th Texas. Major Sanders was shot and had to have his right arm amputated. The initial fighting was followed by uncoordinated and unsuccessful assaults by several Federal brigades. Confederate reinforcements soon arrived, but, as related by another Southern soldier, the Texans were reluctant to give up their position in the front line because, "it was the first time they ever had a chance to fight the Yankees from behind breastworks and that they were rather enjoying it". At 4:00 pm, Cleburne launched a major counterattack by striking the Federals' foothold with Alfred Cumming's brigade in front and the 6th-10th-15th Texas on the right flank. The effort proved entirely successful and chased the Union troops off Tunnel Hill, capturing many prisoners. The 15th Texas sustained losses of one killed, seven wounded, and two missing.
The 6th-10th-15th Texas fought at the Battle of Ringgold Gap on 27 November 1863. Cleburne deployed Granbury's brigade just to the north of the gap. Attacked by Charles R
15th Texas Cavalry Regiment