O’Neill is best known for his activities leading the Fenian raids on Canada in 1866 and 1871.
He was born in Drumgallon, Clontibrit, Co Monaghan, where he received some schooling. He emigrated to New Jersey in 1848 at the height of An Gorta Mór. He received an additional year of education there and worked in a number of jobs.
In 1857 he enlisted in the 2nd United States Dragoons and served in the Utah War (May 1857 – July 1858), apparently deserting afterwards to California.
In California, he joined the 1st Cavalry, and served as a sergeant in the American Civil War with this regiment until December 1862, at which time he was commissioned as an officer in the 5th Indiana Cavalry. He was credited as being a daring fighting officer, but believed he had not received due promotion, which led to a transfer to the 17th United States Coloured Infantry as captain. He left the Union Army prior to the end of the conflict, marrying Mary Crow, with whom he had several children.
While in Tennessee, O’Neill joined the, the Fenian Brotherhood, which eschewed politics in favour of militant action to expel the British presence in Ireland. He attached himself to the group led by William Randall Roberts, who wished to attack Canada.
O’Neill, ranked as colonel, travelled to the Canada–US border with a group from Nashville to participate in the Fenian raids. The assigned commander of the expedition did not appear, so O’Neill took command. On 1 June 1866, he led a group of six hundred men across the Niagara River and occupied Fort Erie.
The following day, north of Ridgeway, Ontario, O’Neill’s group encountered a detached column of Canadian volunteers, commanded by Lt-Col. Alfred Booker (mainly formed of the Queen’s Own Rifles of Toronto and the 13th Battalion of Hamilton). The inexperienced Canadians were routed by the Civil War veterans. O’Neill withdrew back to Fort Erie and fought a battle against a detachment led by John Stoughton Dennis. With overwhelming numbers of Canadian forces closing in, O’Neill oversaw a successful evacuation on the night of 2–3 June back to United States territory. He was later charged with violating the neutrality laws of the USA, but it was dropped.
Ridgeway made O’Neill a Fenian hero. He had won the only success the Fenians ever achieved in their numerous enterprises against Canada. He had handled his force well, and kept his men under strict control and that there was little looting or disorder. The episode shortly led to the Roberts party of the Fenian Brotherhood appointing him president at the end of 1867.
However, the split between two factions of the Fenians remained, and penetration of O’Neill’s organisation by British and Canadian spies ensured that his next venture into Canada in 1870 was known in advance, and Canada was accordingly prepared. After the Battle of Trout River ended in a disorganised rout, O’Neill was arrested by United States Marshal George P. Foster and charged with violating neutrality laws. That led to O’Neill’s imprisonment in July 1870 – he was sentenced to two years – but he and other Fenians were pardoned by President Ulysses S. Grant that October.
Though he renounced the idea of further attacks on Canada, he changed his mind at the urging of an associate of Louis Riel, William Bernard O’Donoghue. With the latter, and without the backing of the bulk of the Fenians, he led an attack on the Hudson’s Bay Company’s post at Pembina, Manitoba, on 5 October 1871. The area was then disputed between America and Canada. He was arrested by American troops.
O’Neill was working for a firm of land speculators in Holt County, Nebraska, in January 1878, when he died of a paralytic stroke.
The Feargal O’Hanlon Lecture is an annual lecture given in memory of Feargal O’Hanlon who died, along with Seán South, when they, along with others, unsuccessfully attacked an RUC Barracks in Brookeborough, Co Fermanagh, on New Year’s Day, 1957. In 2000, the lecture was delivered by Derek Warfield of The Wolfe Tones. The lecture was attended by relatives of Feargal O’Hanlon and by Gerry O’Neill, whose great-grandfather was a brother of John O’Neill.