There is very little in the records as they were newly formed. The following is taken from their bi-monthly muster reports Record of Events. These records may be found in the Supplement to the Official Records and may also be obtained if you have a subscription to fold3.com.

Record of Events

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17th Mississippi Infantry

Field and Staff

Stationed at —, June 7, 1861.
June 7.— Muster-in roll of field and staff in the Seventeenth
Regiment of Mississippi, commanded by —, called into the
service of the Confederate States in the Provisional Army under
the provisions of the Act of Congress passed February —, 1861
by — from June 7, 1861 (date of this muster) for the term of
twelve months, unless sooner discharged. . . .
W. S. WALKER,
Confederate States of Army, Mustering Officer.Captain,

Station not stated, May-October 1861.

Company H
Stationed in camp near Leesburg, Virginia, June 7-August 19,
1861.

Company I
Stationed at Leesburg, Virginia, July-August 1861.

Company K
Stationed at camp near Carter's Mills, Virginia, July-August
1861.

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18th Mississippi Infantry

Field and Staff

Stationed at Corinth, Mississippi, June 7, 1861.
June 7.— Muster-in roll of field and staff in the Eighteenth
Regiment of Mississippi, commanded by Colonel E. R. Burt,
called into the service of the Confederate States in the Provisional
Army under the provisions of the Act of Congress passed Febru-
ary —, 1861 by President Jeff Davis from June 7, 1861 (date of
this muster) for the term of twelve months, unless sooner dis-
charged. . . .
W. S. WALKER,
Confederate States of Army, Mustering Officer.Captain,

Stationed near Richmond, January-June 1862.

Company A
Station not stated, April 12, 1861.

Stationed at Corinth, Mississippi, June 7, 1861.
June 7.— Muster-in roll of Captain Joseph M. Jayne's Company
A, in the Eighteenth Regiment of Mississippi, commanded by
Colonel E. R. Burt, called into the service of the Confederate
States in the Provisional Army under the provisions of the Act of
Congress passed February —, 1861 by — from —, 1861
(date of this muster) for the term of twelve months, unless sooner
discharged. . . .
W. S. WALKER,
Captain,
Confederate States of Army, Mustering Officer.

Stationed at Leesburg, May 24-June 30, 1861.

Stationed at Leesburg, Virginia, July-August 1861.
July 21.— This company was engaged in the battle of Manassas
in the Third Brigade commanded by Brigadier-General [David
Rumph] Jones.

Company B
Stationed near Leesburg, Virginia, May 29-August [31], 1861.

Company G
Stationed at Leesburg, June 3-30, 1861.

Stationed at Leesburg, Virginia, July-August 1861.
July 21.— Participated in battle of Manassas, while in General
Jones' Brigade, in which Captain A. McWillis and Private W. A. Cain were killed; Private Tucker mortally wounded and has since died. Private Allen and [John] Bishop wounded and were discharged.