Stonewall Jackson was selected in January 1862, by Capt. James E. Montgomery to be part of hisRiver Defense Fleet atNew Orleans. On 25 January Montgomery began to convert her into a cottonclad ram by placing a 4-inch (100 mm) oak sheath with 1-inch (25 mm) iron covering on her bow, and by installing double pine bulkheads fitted with compressed cotton bales.
Stonewall Jackson's conversion was completed on 16 March 1862. Under Capt. G. M. Phillips she was detached from Montgomery's main force and sent toForts Jackson andSt. Philip on the lower Mississippi to cooperate in the Confederate defense of New Orleans. There, with five other vessels of Montgomery's fleet, all under Capt. J. A. Stevenson, she joined the force under Capt. J. K. Mitchell, CSN, commanding Confederate naval forces in the lower Mississippi.
On 24 April 1862 a Union fleet underFlag OfficerDavid Farragut, USN,ran past Forts Jackson and St. Philip on its way to capture New Orleans. In the engagementStonewall Jackson rammedUSS Varuna, which had already been struck byCSS Governor Moore. WithVaruna's shot glancing off her bow,Stonewall Jackson backed off for another blow and struck again in the same place, crushingVaruna's side. The shock of the blow turned the Confederate vessel, and she received five 8-inch shells fromVaruna, abaft her armor.Varuna ran aground in a sinking condition, andStonewall Jackson, chased byUSS Oneida coming toVaruna's rescue, was driven ashore and burned.
Engraving published in "The Soldier in Our Civil War", Volume I. It depicts USSVaruna (center), being rammed by a Confederate ship identified as "Breckinridge" (left) while engaging CSSGovernor Moore (right) during the battle off Forts Jackson and St. Philip, 24 April 1862. The ship identified as "Breckinridge", is more probably theStonewall Jackson.