Hello there! As your question is related to looking for identification/information regarding military personnel, our Guide on Military Identification may be of use to you. It provides a number of different resources, including how to request service records from a number of national agencies around the world, as well as graphical aids to assist in deciphering rank, unit, and other forms of badges or insignia. While the users here may still be able to lend you more assistance, hopefully this will provide a good place to start!

Depending on which country he fought for you can use the Commonwealth War graves Commision website, which can provide you with the circumstances of death, any awards he might have received, a brief history of service and even the exact cemetery plot he’s buried in. Here in the UK you can search the completely free census, which will give you details like address, family members in residence, their respective occupations and ages, even wether they had any servants at the time. To find him easily though it would be best if you had his address, full name, and maybe even age. Hope this helps.