You might get an idea of their work in these three reports of the 14th Louisiana Battalion Sharpshooters, there no history of the 15th LA Battalion in the American CW Research Database.
Fourteenth Louisiana Battalion [Sharpshooters]
Stone's River after battle report:
Report of Maj. J. E. Austin, Fourteenth Louisiana Battalion [Sharpshooters].
JANUARY 11, 1863.
CAPT.: Having deployed my command in front of Gen.
Breckinridge's division, in obedience to orders from division headquarters, I
was awaiting the approach of the enemy on the morning of December
31, 1862, when I received an order from division headquarters directing
me to join my brigade. I immediately assembled my command and
marched it rapidly to the place occupied by the brigade a short time
before, but found that it had gone across the river for the purpose of
attacking a strong position that the enemy had taken up near the railroad
and river bank. I accelerated my movements as much as possible, and
came up with the brigade as it was marching upon the enemy's position
in line of battle, and reported to Gen. Adams, commanding, in
person, and asked him where I should take position. The general
informed me that he had already made his dispositions for the attack,
and ordered me to take position about 100 yards in rear of the brigade,
as a reserve. I formed my command as directed, and followed the
brigade as it advanced up the hill, upon which the enemy had planted his
artillery and disposed infantry. Here a furious fight ensued, which lasted
about thirty minutes, when the brigade was forced to fall back before the
terrible flank and front fires of the enemy. Learning from Col.
Gibson, commanding Thirteenth and Twentieth Louisiana Regiments, the
flank movement of the enemy, I changed front forward and formed
along a fence running near and parallel to the railroad. I found the
enemy directly in my front, and opened fire upon him with a staggering
effect. His attention had been drawn just previous to this to the brigade,
which was falling back, and the rapidity of my movement caused a
confusion in his ranks, which, I am of the opinion, was fortunate for the
brigade, for his fire was directed upon me until the brigade had
retreated some distance [almost out of range], when I withdrew with but
little confusion from a contest so unequal, and fell back upon our
artillery, which had been brought up as a support.
On January 2, I was deployed in front of a portion of Gen. Stewart's
line [I think his right], and my command did some excellent service in
driving from the field in front of the cedar thicket a body of the enemy's
skirmishers.
Late on January 2, I was ordered with my command to join the brigade,
which I did, and was placed as a reserve in the celebrate charge of
Friday evening, January 2, in which the [Breckinridge's] division
participated. My command, together with the Thirty--second Alabama
Regiment, constitute the reserves, and were not ordered forward, but
when the shattered battalions fell back they formed upon us.
My officers, without an exception, acted in the most gallant manner.
Capt. [T. W.] Peyton, commanding Company A, was severely
wounded while leading his company.
Lieut.'s [W. Q] Lowd and [A. P.] Martin, of Company A, and [S. R.]
Garrett, and [C. F.] McCarty, of Company B, as well as
Adjt. A. O'Duhigg, deserve the highest praise.
My loss was 4 killed, 9 missing, and 2 wounded.
I am, very respectfully, captain, your obedient servant,
J. E. AUSTIN,
Maj., Comdg. [Fourteenth Louisiana] Batt, of Sharpshooters
Source: Official Records
PAGE 802-29 KY., MID. AND E. TENN., N. ALA., AND SW. VA. [CHAP. XXXII.
[Series I. Vol. 20. Part I, Reports. Serial No. 29.]
....
Two other of their reports are found in the Official Records
PAGE 227-51 KY., SW. VA., TENN., MISS., N. ALA., AND N. GA. [CHAP. XLII.
[Series I. Vol. 30. Part II, Reports. Serial No. 51.]
CHAP. L.] REPORTS, ETC.--CONFEDERATE. PAGE 861-74
[Series I. Vol. 38. Part III, Reports. Serial No. 74.]