Gaelic legend has it that the first Fenians were an elite band of warriors sworn to protect Finn, a medieval Irish monarch. In the mid-nineteenth century their name was adopted for Irish patriots, whether in Ireland or the United States who, courtesy of James Stephens’s Irish Republican Brotherhood, took an oath to expel the British from Ireland by force of arms.  In 1866 the first explicitly Fenian rising was ruthlessly suppressed. Stephens’s boast of 85,000 enlisted Irishmen was fanciful. Irish soldiers who had served with British regiments in India, Africa or China and who had sworn their support to the…