Sidney Lewis was the youngest British soldier to serve in World War I, enlisting at age 12. He fought in the Battle of the Somme in 1916 before being discovered and sent home due to being underage. Lewis had run away from his home in South London to join the army without his mother's permission, motivated by a desire to take part in the Great War. He served with the 106th Machine Gun Corps before his young age was discovered and he was discharged.