As a possibility, there is a Charles Sargent in overseas military records at Jullundur, Punjab, India at 1911, birth noted as 1884 St Catherine, Dublin.
Or, a Charles Sargent b1866 Dublin, listed on attestation papers for Royal Artillery in 1919, with nok listed as a niece, Miss Mulvey, Waltham House, Waltham Terrace, Dublin. Nothing listed under marriage/children. Discharged to an address in Scarborough in 1921.