Joab must have lied his age in order to enlist as men this young wouldn’t have been enrolled.

Suggest you query the Civil War Prison Message Board if they have any information on individual prioners at Point Lookout. I suspect he was captured in hospital soon after the Battle of Murfreesboro/Stone’s River

We just have no idea of what became of Alsey based on the available records

………

A. F. Bennett, age 45, Private, Captain Robins’ Detached Company, Alabama Mounted Volunteers,* enlisted October 22, 1861 in Wilcox County, Ala. for the war, by Maj. Julius Hessee. Q. M., Mobile, Ala., value of horse $110, furloughed to conduct a Corpse home from November 14, 10 days, returned November 25, 1861, no further records

Note, he must have been dropped from the rolls sometime before the next surviving muster roll for the period May/June, 1863. This could have because of death, discharge, desertion, capture, etc.

* The organization subsequently became Company C, 3rd Regiment Alabama Cavalry

……….

Joab Bennett, Private, Company C, 3rd Regiment Alabama Cavalry, enlisted March 10, 1862 at Mobile, Ala. by Capt. Yancy for the war, recorded absent at the July 17, 1863 muster, “left sick near Murfreesboro January 4, 1863,” no further records

M311: Compiled Service Records of Confederate Soldiers Who Served in Organizations from the State of Alabama

………

Birth: unknown
Death: unknown

BENNETT, Joab
Private, Company C, 3rd Alabama Cavalry Regiment
Buried at Point Lookout Maryland.

http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GSln=Bennett&GSfn=Joab&GSiman=1&GScid=81385&GRid=10057800&

………

Stone's River after battle report:

Report of Capt. T. H. Mauldin, Third Alabama Cavalry,
Wheeler's brigade, including skirmishers December 26-January 5.

FOSTERVILLE, TENN., February 19, 1863.

COL.: The Third Alabama Cavalry was engaged in skirmishing
with the enemy on December 26,27,28, and 29, 1862, from La Vergne
to Murfreesborough, Tenn.

On the 30th, was present at a skirmish near Jefferson, La Vergne, and
Lonensville.

On the 31st, was in a charge made by the cavalry upon the right of the
Federal army, where it was subjected to a heavy fire of
small-arms from infantry and cavalry, losing, however, but 1 man killed
and 2 lieutenants and 2 men wounded and left on the field.

On January 1 and 2, the regiment was in front of the enemy upon the
extreme left of the Confederate army without any fighting.

On the night of the 2d, it marched to the rear of the Federal army, and
on the 3d was engaged in an attack upon one of the enemy's wagon
trains, upon the Nashville Murfreesborough turnpike, and returned to
the field of battle near Murfreesborough about an hour before day the
morning of the 4th.

During the day of the 4th, this regiment moved through
Murfreesborough, and bivouacked at night about 2 miles from town, on
the Manchester turnpike.

On the 5th, was engaged in a fight with some of the Federal infantry 6
miles from Murfreesborough, on the Manchester pike.

This ended the series of battles and skirmishers from December 25,
1862, to January 5, 1863 in which the regiment was engaged.

During this time the regiments lost, in killed, wounded, and missing,
25, including 3 lieutenants wounded.

I would respectfully report that on the memorable field of
Murfreesborough, Sergt. Maj. H. M. Cooper and Sergt. J. W. Norwood, of
Company A, are worthy of promotion for their gallantry in rallying the
regiment and assisting in bringing it out in order from under a galling
fire from the enemy's infantry and cavalry combined on December
31, 1862.

Very respectfully, your obedient servant,

T. H. MAULDIN,
Capt., Cmdg. Third Alabama Cavalry.

Col. W. B. WADE,
Cmdg. First Cavalry Brigade.

Source: Official Records
PAGE 962-29 KY., MID. AND E. TENN., N. ALA., AND SW. VA. [CHAP. XXXII.
[Series I. Vol. 20. Part I, Reports. Serial No. 29.]