Charles Eaton was born on 21 December 1895 in Lambeth, London, the son of William Walpole Eaton, a butcher, and his wife Grace. Schooled in Wandsworth, Charles worked in Battersea Town Council from the age of fourteen, before joining the London Regiment upon the outbreak of World War I in August 1914. Attached to a bicycle company in the 24th Battalion of the 47th Division, he arrived at the Western Front in March 1915. He took part in trench bombing missions and attacks on enemy lines of communication, seeing action in the Battles of Aubers Ridge, Festubert, Loos, and the Somme.