Battery I moved from Memphis on 6–11 June 1863 to join the Siege of Vicksburg. The siege was successfully concluded on 4 July. During the siege, the battery was commanded by Lieutenant Lansing and reported to William Sooy Smith who led the 1st Division and Cadwallader C. Washburn who led the XVI Corps contingent. The battery took part in the Jackson Expedition, marching to Jackson, Mississippi on 4–10 July and laying siege to the city on 10–17 July. One source asserted that the unit served in the 4th Division, XV Corps from July 1863 to April 1864. Another authority stated that W. S. Smith's 1st Division changed its designation to 4th Division, XV Corps in September 1863. Battery I guarded the Big Black River until 25 September when it traveled to Memphis. The battery moved to Chattanooga, Tennessee between then and 23 November. During that period, the unit took part in operations on the Memphis and Charleston Railroad in northern Alabama on 20–29 October.