Hello,
So many years after your initial posting, but I am going to try to help. There is a Daniel Gahan, born 1847 and died July 19,1912, buried in Calvary Cemetary in Springfield, Illinois. He is buried right near my relatives, Michael Summers (or Sommers) and wife, Marguerite Devereaux, both from Wexford, both born 1825. I was investigating him as possibly a nephew to Devereaux. The relatives are often buried nearby. It said that he was born in Ireland and survived by wife and son, Danny.
As I was searching for this in my newspaper clippings, I also found a Dennis Gahan who died in Springfield, IL. on Sept. 2, 1949 and was born Jan.23, 1884, in Springfield. This may be of no use to you, but I thought I would send it out anyway. Good luck. Stay in touch please because Gahan is a name that is connected to Devereaux and Sommers, all of whom came from Wexford, via Canada, and on to Springfield, Illinois.
Additional info that I found that I had includes a Margaret Devereaux (not mine!)born 1828 in Monageer, Wexford. She died in 1870, and her parents were Thomas Devereaux and Margaret Gahan.
Advice: when you get stuck research relatives. I did that and found relatives related to my great grandmother, and they had wonderful pictures of my great great grandmother and tons of info. Good luck.
Mary