First to Martin.
The first mention I ever encountered of the term "Harp without the Crown" was in the book "Year of the French" which dealt with the ill-fated landing of the French in Ireland in 1798. Not necessarily authoritative, but the basis for my first statement.
And to Mark D:
Try and Get ahold of the Disc "The Irish in America" which contains a song called "By the Hush, Me Boys", in which the singer is lamenting his coming to America and being drafted into the Northern Army. It might appropriate to your needs.
Keep the Faith.
Jack Hickman