Looking for info on Flanagans in Armagh

I am looking for any information at all about my great grandfather who came from Armagh . His name was Lawrence Flanagan and it would have been around the mid to late 1800's. He emigrated to America, but I can find no record on this end. He had a son named Michael Lawrence who married Catherine O'Neill. I believe her family is also from Armagh. Any information would be greatly appreciated.