See John D. Winters "The Civil War in Louisiana" (LSU Press, 1963), pp. 231-232.

It wasn't Sherman, it was Banks!

Colonel W. K. Kimball with the 12th Maine, 41st Massachusetts, a section of Nims' battery, and one company of the 24th Connecticutt paid Avery Island a visit on April 16, 1863. According to Dr. Winters: "After his all-night march Kimball advanced to the beautiful little island, and without opposition, burned eighteen buildings, smashed the steam engines and mining equipment, scattered 600 barrels of salt awaiting shipment, and brought away a ton of gun powder left behind by Taylor's men."

Some 10,000 men from Sherman's army in Mississippi under the command of Brigadier General A. J. Smith arrived aboard river transports at Simsport on March 12, 1864, captured Fort DeRussy and participated in the Mansfield/Pleasant Hill campaign. They retreated to Simsport and embarked for Vicksburg on May 22, 1864. Smith's "gorillas" did a lot of damage along the Red River in the 42 days they were on the ground but they were not in southern Louisiana. See Richard B. Irwin, Lieutenant Colonel, U.S.V., Assistant Adjutant General, Department of the Gulf, "The Red River Campaign", Battles and Leaders of the Civil War, Volume IV (Castle Books Reprint, 1956) pp. 349, 360.