I'm not sure that Samuel and John Splan(e) were soldiers. I found their names on a list of Beckwith settlers and it was entitled:
1816-1822 Settlers Beckwith Township
Lanark County, Ontario, Canada
(Civilian Settlers who were eligible for Crown Land Patents/Grants)
Samuel came over from Ireland in Dec. 1821 on the ship Martha and John came from Ireland in Dec. 1822.
I looked up the land grant but wasn't able to get a copy at the time. I don't recall it saying anything about military service. I really must get back and get a copy.
I don't have a Thomas Splane born 1771. The oldest Thomas I have was born about 1800 in Ireland, son of Samuel.
I have never found the relationship between John and Samuel but I'm sure there was one - probably brothers.
I have also never found a relationship between the Beckwith Splans and the Toronto Gore family.
If you find anything I would love to hear from you again.