O'Mahony, John(ōmă`hənē), 1816–77, Irish patriot. He attended Trinity College, Dublin, and became a proficient Irish scholar. After taking part in the unsuccessful Young Ireland rebellion of 1848, he fled to France and from there to the United States, where he was a founder and organizer of the Fenian movementFenian movement
secret revolutionary society organized c.1858 in Ireland and the United States to achieve Irish independence from England by force.
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