Frances, My Grandfather, Dan O'Hegarty - name changed to Haggerty upon immegration, moved to NY in the 1890s. He was about 16 years old, so not the bare-knuckler you're looking for. He became a Mounted Policeman in NYC and owned a pub on Long Island when he retired and passed away in 1953. Following is a little history that I picked up from this forum a couple of years ago.
"In 1601 the Hegartys (Haggertys), Sullivans, and O'Neills came from Donegal to Cork to fight the English, with the Spanish, in the Battle of Kensale on Xmas eve, 1601, and 289 Hegartys were killed out of 300. The 11 stayed in Cork. The Hegartys had a castle in Donegal and controled a 20 mile by 2 mile strip of land between Lough Swilly and Lough Foley (Londonderry). The Hegartys left in Donegal lost everything and fled to France with the "Wild Geese" but kept ties to Ireland and fought the English over and over again. We have a castle in Austria that I have been to."
Love to hear how the search goes, seems we have a very colorful heritage! Explains a lot about my own disposition!