Charles Gerard Conn was born in Phelps, New York, on January 29, 1844. In 1850, he accompanied his family to Three Rivers, Michigan, and in the following year to Elkhart, Indiana. Little is known about his early life, other than that he learned to play the cornet. With the outbreak of the American Civil War he enlisted in the United States Army on May 18, 1861 at the age of seventeen, despite his parents' protests. On June 14, 1861, he became a private in Company B, 15th Regiment Indiana Infantry, and shortly afterwards was assigned to a regimental band. When his enlistment expired he returned to Elkhart, but re-enlisted on December 12, 1863, at Niles, Michigan, in Company G, 1st Michigan Sharpshooters. At the age of nineteen on August 8, 1863, he was elevated to the rank of captain. During the Assault on Petersburg on July 30, 1864, Conn was wounded and taken prisoner. In spite of two imaginative and valiant attempts to escape, he was recaptured and spent the remainder of the war in captivity. At the end of hostilities, he was released from Columbia, South Carolina prison camp, and was honorably discharged on July 28, 1865. He was one of only six Union soldiers to be retroactively awarded the Silver Citation Star on the Civil War Campaign Medal for gallantry in action.