John Lincoln Clem ran off from Newark, Ohio, with the 22nd Michigan Infantry when he was 10 years old. Since the 22nd was not mustered until 29 Augut 1862, it is unlikely that he served at Shiloh. In time, he became the regimental mascot, and was enlisted as a drummer boy in Company O. The soldiers of the 22nd cut down a ".54" caliber Muster 1854 Austrian infantry rifle to Clem's size, and he was carrying it at Chickamauga when he was twelve. During the battle, Clem became separated from his unit, and was seen by a Confederate colonel, who demanded the boy's surrender. When Clem declined to surrender, the courageous Confederate cavalier drew his sword to ride the boy down. Clem brought up his rifle, and blew the colonel out of his saddle with one well placed shot, seriously wounding him. Clem was promoted to corporal, and awarded the "badge of the roll of honor" by Major General William S. Rosecrans for his actions at Chickamauga. Given that the Federal Army had no awards for valor other than the Medal of Honor, the award would probably be similar to the modern Bronze or Silver Star medal.
In 1871, Clem was nominated for an appointment to the U.S. Military Academy, with the nomination being endorsed by Generals Grant, Sherman, and Sheridan. But, he could not pass the entrance examination due to deficiencies in his education resulting from his wartime service. President U.S. Grant then gave him a direct appointment as a second lieutenant in the 24th Infantry, one of the two black infantry regiments in the post-Civil War U.S. Army. Clem retired in August 1915 as a major general, and as the last Civil War veteran serving on active duty in the U.S. Army.