This may interest you. A son recognised an old picture of his dad in a Remembrance Sunday newspaper feature about WW1's boy soldiers. His dad enlisted in the British Army in August 1915 at the age of 12 years and 4 months, fought on the Somme, and was only discovered and discharged in August 1916. In later years he mentioned that he'd been involved in the Great War, but the son hadn't believed him!
http://www.abroadintheyard.com/identity-of-12-year-old-ww1-veteran-revealed/