Battery "M", 2nd Illinois Light Artillery Regiment was an artillery battery from Illinois that served in the Union Army during the American Civil War. The battery was organized in June 1862 at Springfield, Illinois. The unit was assigned to guard the railroad in West Virginia and was captured and paroled when Harpers Ferry surrendered in September 1862. After exchange, the battery took part in the Knoxville campaign in the fall and winter of 1863. The unit was stationed in Kentucky until it was mustered out in April 1864. Personnel were transferred to Battery "C" and Battery "H", 2nd Illinois Light Artillery Regiment.