My great-grandfather was Richard Thomas O'Hagan (1882-1956), born in Dickerson, Maryland; died in Lodi, California. His parents were Clarence O'Hagan and Margaret Sullivan, both of Ireland.
I have been unable to find any records from Maryland in any form for Clarence O'Hagan and was intrigued by its use as a family name in your family. Interestingly, Richard O'Hagan lived in El Paso for a few years in the early 30's, where my grandfather Ralph O'Hagan was born in 1931. Any information you have on the most senior Clarence C. O'Hagan in your line I'd greatly appreciate, as I'm hoping there is a connection.