The little drummer boy of the Civil War
When President Abraham Lincoln in May 1861 issued the call for volunteers to serve in the Union army for a three year term, one of those who tried to answer was Ohio resident John Clem. Not yet 10 years old, Clems service was refused by the newly formed 3rd Ohio. Undeterred, Clem later tried to join the 22nd Michigan, where his persistence won over the units officers. They agreed to let him follow the regiment, adopting him as a mascot and unofficial drummer boy. The officers also chipped in to pay his monthly salary of $13 before he finally was allowed to officially enlist in 1863.
Article goes on to highlight his life story. Again enlisting in the army after the Civil War-
He retired on the eve of U.S. entry into World War I with the rank of major general, the last Civil War veteran to actively serve in the U.S. Army. Clem died on May 13, 1937 and is buried at Arlington National Cemetery
http://www.vintag.es/2018/04/john-clem.html