Fenian was an umbrella term for the
Fenian Brotherhood and
Irish Republican Brotherhood (IRB), fraternal organisations dedicated to the establishment of an independent
Irish Republic in the 19th and early 20th century. The name
Fenian was first applied by
John O'Mahony to the members of the
Irish republican group that he founded in the United States in 1848. O'Mahony, who was a
Celtic scholar, named the American wing of the movement after the
Fianna. In
Gaelic Ireland these were warrior bands of young men who lived apart from society and could be called upon in times of war.