Soon after the outbreak of the
American Civil War, on July 16, 1861, Sweet joined the
6th Wisconsin Volunteer Infantry Regiment of the
Union Army and was given the rank of
major. On September 17, 1861, he was promoted to
lieutenant colonel. Sweet's efforts to prevent the conspirators from achieving their objective earned him the thanks of the
United States Department of War. On December 12, 1864, President Lincoln awarded Sweet the rank of
brevet brigadier general of volunteers to rank from December 20, 1864, and the U.S. Senate confirmed the award on February 14, 1865. Sweet resigned from the army on September 19, 1865. He died from a sudden illness in 1874. ==References==