I suspect the man you are looking for was Private S. W. Blanchard of Company H, 1st Mississippi Cavalry. His files contains one card, a requsition for medical and hospital supplies recording him as Acting Surgeon of Captain Gadi Herron's, Co. H.
George Martin
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John Alex Blanchard of Louisiana, appointed Assistant Surgeon November 3, 1864 to take rank February 11, 1864, Spaight's Batt., on duty at Beaumont, Texas during June 1864, dropped upon consolidation of Regiment November 20, 1864 [M331]
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L. W. Blanchard, Ass't. Surgeon, cards filed with S. W. Blanchard, Company H, 1st Mississippi Cavalry [M331]
S. W. Blanchard,Private Company H, 1st Mississippi Cavalry, enlisted July 31, 1862 at Bolivar County, died near Rough & Ready Station August 26, 1864
Acting Surgeon stationed at Jackson, Mississippi issued a requisition for medical and hospital supplies for the month of December 1862 for Cavalry Captain Gadi Herren [Co. H, 1st Mississippi Cavalry] [M269]