Battery "M", 1st 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 August 1862 at Chicago and was on duty in Kentucky until January 1863. The battery served in the Tullahoma campaign, at Chickamauga and Missionary Ridge, and in the Knoxville, and Atlanta campaigns. Thereafter, the unit garrisoned Chattanooga, Tennessee until it was mustered out in July 1865.