The unit was made up of men from the Texas counties of Anderson, Bosque, Coryell, Erath, Fannin, Freestone, Grimes, Harris, Johnson, Limestone, Milam, Parker, San Augustine, and Washington.

Nelson was a veteran of the Mexican–American War and had become involved in filibuster Narciso López's unsuccessful attempt to free Cuba from Spanish control.

[1] Nelson was promoted brigadier general on 12 September 1862 while the regiment camped at DeValls Bluff, Arkansas under the overall command of Thomas C. Hindman.

[1] In the Battle of Arkansas Post, the 5,000 Confederate defenders under Thomas James Churchill were attacked by 30,000 Union troops led by John Alexander McClernand and 13 gunboats under David Dixon Porter.

The Federal expedition sailed up the Arkansas River in 50 transports and landed the soldiers below the post on 9 January 1863.

From 31 July to 1 September 1863, the consolidated regiment served in Churchill's brigade of Patrick Cleburne's division in Daniel Harvey Hill's corps.

[1] Early in the morning of 24 November, William T. Sherman's forces crossed the Tennessee River and moved toward the northern edge of Missionary Ridge.

Braxton Bragg, the commander of the Confederate Army of Tennessee was slow to respond, but finally ordered Cleburne to block Sherman's troops.

In the late afternoon, Cleburne deployed Smith's brigade on Tunnel Hill just in time to prevent Union soldiers from seizing it.

A counterattack hurled the Federal troops back, but both Smith and Colonel Mills were badly wounded.

Confederate reinforcements soon arrived, but, according to another Rebel soldier, the Texans refused to yield their place in the front line, saying, "it was the first time they ever had a chance to fight the Yankees from behind breastworks and that they were rather enjoying it".

[12] At 4:00 pm, Cleburne mounted a counterattack by hitting the Federals with Alfred Cumming's brigade in front and the 6th-10th-15th Texas on their right flank.

The effort was completely successful and swept the Union troops off Tunnel Hill, taking many prisoners.

When they were attacked by Charles R. Woods's Union brigade, the Texans routed the three leading Missouri regiments.

[1] At Franklin, the Confederate soldiers assaulted the Union lines with great determination and persistence, but they were ultimately repulsed.