Denis is believed to have farmed in the Boolymore/Knockbrack/Fortgrady/Carragraigue area of Dromtarriff, although the baptism records for his oldest children appear to say they were from "Glaundaeagh(?)" - a townland that has not been identified and may now be obsolete. The 1853 Griffith's Valuation may list him with two brothers (Timothy and John) in Carragraigue.
Denis' younger sister Ann married a John Wallace in 1833 and started raising a family in Boolymore, and later Knockbrack. That Wallace family left Ireland around 1845 and settled in Jackson County, Iowa - south of Dubuque. Ten years later, in 1855, Denis arrived in Iowa with his own family - settling first in Jackson County, very near to his Wallace relatives, and then in neighboring Dubuque County, Iowa, still just a few miles from his sister. Denis farmed near to the New Melleray Monastery, and was buried in Holy Family Cemetery about a quarter mile from the monastery.