After the regiment moved into Arkansas, it became subject to the First Conscription Act and was reorganized on 20 May 1862.
Due to the Act, about 100 soldiers were discharged for being too young or too old.
The Act also specified that the soldiers could elect their own officers.
Sweet was reelected colonel, George Bibb Pickett became lieutenant colonel, and William Henry Cathey became major.
Soon afterward, Pickett of Wise County was sent home to Decatur, Texas to recruit.
On 8 July 1862, the regiment was involved in a skirmish with Federal forces at Batesville, Arkansas in which eight men were killed and seven wounded.
Sweet commended Captain Valerius P. Sanders of A Company for "coolness and bravery" under fire.
A Union force under Samuel Ryan Curtis numbering 6,000 infantry, 3,000 cavalry, and 1,000 artillerymen occupied Batesville by 1 June.
Hoping to cut off Curtis's troops from supplies, Thomas C. Hindman ordered Sweet's regiment to cross the White River above Batesville.
Hindman claimed 200 Union troops were captured and a number of wagons were captured before Cadwallader C. Washburn's Union cavalry brigade compelled the Texans to retreat.
Soon after, on 24 July, the regiment was dismounted and the men's horses sent home.
The soldiers were never remounted and served through the rest of the war as infantry.
Cathey resigned for health reasons on 21 October 1862 and was replaced as major by Sanders.

The 15th Texas Cavalry was ordered to garrison Arkansas Post in the late fall of 1862.
The place proved to be a very unhealthy campsite and over 100 men from the regiment died from disease while others were sent home as unfit for duty.
About this time, Colonel Sweet left the regiment on detached duty and ended the war as superintendent of Camp Ford, a prisoner-of-war camp.
The 15th Texas Cavalry under Major Sanders was assigned to James Deshler's brigade along with the 10th Texas Infantry, and the 17th and 18th Texas Cavalry Regiments, fighting dismounted.
In the Battle of Arkansas Post, 30,000 Federal troops led by John Alexander McClernand and 13 gunboats under David Dixon Porter attacked the 5,000 Confederate defenders under Thomas James Churchill.
The Union expedition steamed up the Arkansas River in 50 transports and on 9 January 1863 landed the soldiers downstream from the post.
The next day, the Federal troops began to envelop the Confederate defenses.
That night Churchill received orders to hold Arkansas Post at all costs.
On 11 January 1863, a joint land and naval assault silenced Fort Hindman's guns and overwhelmed the defenders, forcing 4,791 Confederates to surrender.
Federal casualties numbered 1,061.

In the 15th Texas Cavalry 27 officers and 436 rank and file became prisoners of war.
The regiment's number of killed and wounded is unknown, but Assistant Surgeon Nathan Wyncoope was fatally wounded during the fighting.
The officers were sent to Camp Chase in Ohio, while the enlisted men traveled to Camp Douglas in Chicago.
About 700 of the captured Texans died in only two months of captivity, including approximately 100 men from the 15th Texas Cavalry.
The death toll was made worse because a number of the men caught pneumonia and other illnesses on the trip up the river and because few of the men had blankets.
On 3 April 1863, the surviving rank and file were sent to City Point, Virginia for prisoner exchange and on 29 April the officers were sent to Fort Delaware.
The ordeal of the enlisted men was worse than that of the officers.
Many of the survivors were so ill that they subsequently died or were discharged sick.
Because this resulted in a surplus of officers, about two-thirds of the officers were sent back to Texas.
The remaining soldiers of the 15th Texas Cavalry were consolidated into a single regiment together with the 6th Texas and 10th Texas Infantry.
Major Sanders stayed with the new formation.
After the regiment moved into Arkansas, it became subject to the First Conscription Act and was reorganized on 20 May 1862. Due to the Act, about 100 soldiers were discharged for being too young or too old. The Act also specified that the soldiers could elect their own officers. Sweet was reelected colonel, George Bibb Pickett became lieutenant colonel, and William Henry Cathey became major. Soon afterward, Pickett of Wise County was sent home to Decatur, Texas to recruit. On 8 July 1862, the regiment was involved in a skirmish with Federal forces at Batesville, Arkansas in which eight men were killed and seven wounded. Sweet commended Captain Valerius P. Sanders of A Company for "coolness and bravery" under fire. A Union force under Samuel Ryan Curtis numbering 6,000 infantry, 3,000 cavalry, and 1,000 artillerymen occupied Batesville by 1 June. Hoping to cut off Curtis's troops from supplies, Thomas C. Hindman ordered Sweet's regiment to cross the White River above Batesville. Hindman claimed 200 Union troops were captured and a number of wagons were captured before Cadwallader C. Washburn's Union cavalry brigade compelled the Texans to retreat. Soon after, on 24 July, the regiment was dismounted and the men's horses sent home. The soldiers were never remounted and served through the rest of the war as infantry. Cathey resigned for health reasons on 21 October 1862 and was replaced as major by Sanders.
The 15th Texas Cavalry was ordered to garrison Arkansas Post in the late fall of 1862. The place proved to be a very unhealthy campsite and over 100 men from the regiment died from disease while others were sent home as unfit for duty. About this time, Colonel Sweet left the regiment on detached duty and ended the war as superintendent of Camp Ford, a prisoner-of-war camp. The 15th Texas Cavalry under Major Sanders was assigned to James Deshler's brigade along with the 10th Texas Infantry, and the 17th and 18th Texas Cavalry Regiments, fighting dismounted. In the Battle of Arkansas Post, 30,000 Federal troops led by John Alexander McClernand and 13 gunboats under David Dixon Porter attacked the 5,000 Confederate defenders under Thomas James Churchill. The Union expedition steamed up the Arkansas River in 50 transports and on 9 January 1863 landed the soldiers downstream from the post. The next day, the Federal troops began to envelop the Confederate defenses. That night Churchill received orders to hold Arkansas Post at all costs. On 11 January 1863, a joint land and naval assault silenced Fort Hindman's guns and overwhelmed the defenders, forcing 4,791 Confederates to surrender. Federal casualties numbered 1,061. 
In the 15th Texas Cavalry 27 officers and 436 rank and file became prisoners of war. The regiment's number of killed and wounded is unknown, but Assistant Surgeon Nathan Wyncoope was fatally wounded during the fighting. The officers were sent to Camp Chase in Ohio, while the enlisted men traveled to Camp Douglas in Chicago. About 700 of the captured Texans died in only two months of captivity, including approximately 100 men from the 15th Texas Cavalry. The death toll was made worse because a number of the men caught pneumonia and other illnesses on the trip up the river and because few of the men had blankets. On 3 April 1863, the surviving rank and file were sent to City Point, Virginia for prisoner exchange and on 29 April the officers were sent to Fort Delaware. The ordeal of the enlisted men was worse than that of the officers. Many of the survivors were so ill that they subsequently died or were discharged sick. Because this resulted in a surplus of officers, about two-thirds of the officers were sent back to Texas. The remaining soldiers of the 15th Texas Cavalry were consolidated into a single regiment together with the 6th Texas and 10th Texas Infantry. Major Sanders stayed with the new formation.
15th Texas Cavalry Regiment