The 18th Battalion SC Heavy Artillery (aka SC Siege Train) was formed with three batteries of light artillery in May 1862, and subsequently converted to heavy artillery. A fourth battery was added later that year. The battalion spent most of the war in and around Charleston, until withdrawn to NC in early 1865. It was included in the surrender at Durham Station, NC, on 26 Apr 1865. A good source of information on the battalion is: Ripley, Warren, ed., SIEGE TRAIN: THE JOURNAL OF A CONFEDERATE ARTILLERYMAN IN THE DEFENSE OF CHARLESTON, (Columbia, SC: 1986).

Can't tell you much about Dr. White, except that his first name was Octavious.

Hope this helps.