« Reply #2 on: Sunday 24 September 23 22:12 BST (UK) »
The parish register of Templemore has their marriage on 20 January 1836.
https://registers.nli.ie/registers/vtls000632698#page/152/mode/1upWitnesses John Brien and Catherine Guilbride.
'95th' is written beside John's name, which is presumably his regiment.
Edit!**From another site
https://www.curiousfox.com/uk/mbprof2.lasso?eid=152650&-nothingJohn Casey b c1806 Askeaton
Hi, Our John b 1806, enlisted with the 95th Regiment of Foot, Derbyshire Regiment, m Mary Carroll whilst at Templemore. He was discharged from the army in 1841 and in 1847 during the famine accepted an offer from the NZ government to emigrate and as ex soldiers they formed a defensive settlement around Auckland during the Maori wars. Have no details of his family, would welcome any information. Kind regards Allison, NZ
edit2**There is a baptism to a John Casey 95th Regt. and Mary Carroll of a Margaret Casey, 29 September 1838 in Newry parish. Co. Down. Sponsors John Cummins and Ellen Breen.
https://registers.nli.ie/registers/vtls000633286#page/144/mode/1up
Coffey, Cummins [Rathfalla, Tipperary], Cummins [Skirke, Laois], Curran, Dillon [Clare], Fogarty [Garran, Laois/Tipp], Hughes, Keshan (Keeshan), Loughman [Harristown and Killadooley, Laois], Mallon [Armagh], Malone, Markham [Caherkine, Clare], McKeon(e) [Sligo/Kilkenny/Waterford], McNamara, Meagher, Prescott [Kilkenny/Waterford/Wexford?], Rafferty, Ryan, Sullivan, Tobin
GEDMatch: T665306 tested with Family Tree DNA and also with ancestry
GEDCOM file: 1980344