In 1837 Lewis Topography gives a history of Kilkenny City.
There was a British fort there from 1173, later a Garrison with 200 horse and 1000 foot and reduced by plague to 300.
In 1837 there was Infantry Barracks with 15 officers and
558 non-commissioned officers and privates, and a temporary
barracks for a squadron of horses. There were possibly other barracks in County Kilkenny but not mentioned.
You can see this by just googling Lewis Topographical Dictionary or some libraries in Ireland and also www.failteromhat.com
The British Army records were kept at the National Archives in Kew. They now have given access to a pay-website for
the military records. There were births, deaths and marriages on this website for Army personnel.I used to have a membership and I believe you can get a short subscription. If you want the name of the website you will need to contact me as being commercial I can't put it on the message board. You can see the link on the National Archives, UK website.
There is a military message board on line for discussion of military information in Ireland. They know where to look.
google MILGENIRE, Military Genealogy Ireland.
I don't think there is much else I can do for you at this time as I don't have a name. I do have the 1841 & 1871 UK Census that only has Irish born persons. There are over 600 Campbells but without a name!