The national reverse genealogy program is working to reconnect 70 million Irish “Diaspora” back to their place of origin in Ireland. They don’t want to wait for people searching back to Ireland; they want to find out who is here and search in the other direction. They can be contacted at www.irelandxo.com.
The National Archives of Ireland can be contacted at www.nationalarchives.ie. They have census and other records available with more being added. 1913-1922 Irish military records are at www.militaryarchives.ie.
British Army records including Irish regiments are at www.nationalarchives.gov.uk. The National Library at www.nli.ie. have lists of Irish and British Army personnel from the late 19th and early 20th centuries. One may want to check out Dublin City Library and Archives at www.dublincity.ie.