On 25 March 1863, while commanded by Colonel Charles Rivers Ellet, "Switzerland" joined the ram in an attempt to pass the Vicksburg fortress. Both ships were heavily hit by Confederate gunfire, with "Lancaster" being sunk. Despite her damage, "Switzerland" survived the trip and made a subsequent successful passage of the fortifications at Grand Gulf, Mississippi, on 31 March. She took part in operations on the Red and Atchafalaya rivers in May and June 1863. Later in the war, "Switzerland" was part of the Mississippi Marine Brigade.