I'm not familiar with this battalion. However, reserve units raised under the law of Feb. 17, 1864, had the following purpose:

SEC. 5. That all white male residents of the Confederate States, between the ages of seventeen and eighteen and forty-five and fifty years shall enroll themselves..., the time allowed not being less than thirty days for those east...of the Mississippi river, and any person who shall fail so to enroll himself, without a reasonable excuse therefore…, shall be placed in service in the field for the war.... as though he were between the ages of eighteen and forty-five: provided that the persons mentioned in this section shall constitute a reserve for state defence and detail duty....