The Fenian raids were a series of incursions carried out by the Fenian Brotherhood, an Irish republican organization based in the United States, on military fortifications, customs posts, and other targets in Canada (called British North America until 1867) in 1866, and again from 1870 to 1871. A number of separate incursions by the Fenian Brotherhood into Canada were undertaken to bring pressure on the British government to withdraw from Ireland, although none of these raids achieved their aims.

While authorities in the United States arrested the men and confiscated the arms of the Fenian Brotherhood, there was speculation that some in the U.S. government ignored the preparations undertaken by the Fenians due to anger over British assistance to the Confederacy during the American Civil War. The Fenian raids were one of the factors that led to Canadian Confederation, as the provinces united to face the threat of invasions.

Raids Early raids (1866) Abortive raid from Dedham, Massachusetts In Massachusetts, the Dedham chapter of the Fenian Brotherhood, which had offices in the Norfolk House, hosted a meeting at Temperance Hall in which a raid into Canada was organized. John R. Bullard, a recent Harvard Law School graduate, was elected moderator of the meeting and, having been swept up in his own sudden importance and fever of the meeting, ended his animated speech by asking "Who would be the first man to come forward and pledge himself to go to Canada and help free Ireland?" The first of the roughly dozen men to sign the "enlistment papers" were Patrick Donohoe and Thomas Golden. Thomas Brennan said he could not participate, but donated $50 to the cause. The meeting ended with the group singing "The Wearing of the Green." The raid was a failure. Some of the men got as far as St. Albans, Vermont, but none made it to Canada. U.S. authorities arrested a few, and some had to send home for money.

New Brunswick

This abortive Fenian raid occurred in April 1866, at Campobello Island, New Brunswick. A Fenian Brotherhood war party of over 700 members under the direction of Bernard Doran Killian arrived at the Maine shore opposite the island intending to seize Campobello from the British. Royal Navy officer Charles Hastings Doyle, stationed at Halifax, Nova Scotia, responded decisively. On 17 April, he left Halifax with several warships carrying over 700 British soldiers and proceeded to Passamaquoddy Bay, where the Fenian force was concentrated. This show of force discouraged the Fenians, and they dispersed. The invasion reinforced the idea of protection for New Brunswick by joining with the neighbouring colonies of Nova Scotia and the Province of Canada to form the new Dominion of Canada.

Canada West After the Campobello raid, the "Presidential faction" led by Fenian founders James Stephens and John O'Mahony focused more on fundraising for rebels in Ireland. The more militant "Senate Faction" led by William R. Roberts believed that even a marginally successful invasion of the Province of Canada or other parts of British North America would provide them with leverage in their efforts. After the failure of the April attempt to raid New Brunswick, which had been blessed by O'Mahony, the Senate Faction implemented their own plan for invading Canada. Drafted by the senate "Secretary for War" General T. W. Sweeny, a distinguished former Union Army officer, the plan called for multiple invasions at points in Canada West (now southern Ontario) and Canada East (now southern Quebec) intended to cut Canada West off from Canada East and possible British reinforcements from there.Civil War Vets Wanted to Invade Canada to Liberate Ireland By Blake Stilwell, 15 Mar 2019, military.com Key to the plan was a diversionary attack at Fort Erie from Buffalo, New York, meant to draw troops away from Toronto in a feigned strike at the nearby Welland Canal system. This was the only Fenian attack, other than the Quebec raid several days later, which was launched in June 1866.

About 1000 to 1300 Fenians crossed the Niagara River in the first 14 hours of June 1 under Colonel John O'Neill.The Fenian raid at Fort Erie, June the first and second, 1866: with a map of the Niagara Peninsula, shewing the route of the troops, and a plan of the Lime Ridge battle ground. Toronto: W. C. Chewett & Co., 1866. Sabotaged by Fenians in its crew, the U.S. Navy's side-wheel gunboat did not begin intercepting Fenian reinforcements until 2:15 p.m.—14 hours after Owen Starr's advance party had crossed the river ahead of O'Neill's main force.Log Entry, Friday June 1, 1866, USS Michigan Logbook No. 16, July 24, 1864, to August 30, 1866: Logbooks of U.S. Navy Ships, 1801–1940, Records of the Bureau of Naval Personnel, 1798–2003, RG24. (National Archives Building, Washington, DC) NARA.E. A. Cruickshank, "The Fenian Raid of 1866", Welland County Historical Society Papers and Records, Vol 2, Welland Canada: 1926. p. 21; John O’Neill, Official Report of the Battle of Ridgeway, Canada West, Fought on June 2, 1866 (June 27, 1866), New York: John A. Foster, 1870. pp. 37–38 Once the USS Michigan was deployed, O'Neill's force in the Niagara Region was cut off from further supplies and reinforcements.

After assembling with other units from Canada and travelling all night, Canadian troops advanced into a well-laid ambush by approximately 600–700 Fenians the next morning north of Ridgeway, a small hamlet west of Fort Erie. (The Fenian strength at Ridgeway had been reduced by desertions and deployments of Fenians in other locations in the area overnight.)O'Neill's strength in the Fenian camp at Frenchmen's Creek was estimated at 250 by a Canada West Frontier Police detective who infiltrated the camp. He also reported that later in the night an additional 200 Fenians joined the column from the camp, bringing the total to at least 450. See: Detective Charles Clarke to McMicken, telegram, June 2, 1866, MG26 A, Volume 237, p. 103878 [Reel C1663] Canada Archives.Peter Vronsky, Ridgeway: The American Fenian Invasion and the 1866 Battle That Made Canada, Toronto: Penguin-Allen Lane, 2011. pp. 46–47

Canadian Militia troops at the Battle of Ridgeway consisted of inexperienced volunteers with no more than basic drill training but armed with Enfield rifled muskets equal to the armaments of the Fenians. A single company of the Queen's Own Rifles of Toronto had been armed the day before on their ferry crossing from Toronto with state-of-the-art seven-shot Spencer repeating rifles, but had not had an opportunity to practise with them and were issued with only 28 rounds per man. The Fenians were mostly battle-hardened American Civil War veterans, armed with weapons procured from leftover war supplies, either Enfield rifled muskets or the comparable Springfield.Fenian Brotherhood. Proceedings of the second National Congress of the Fenian Brotherhood, held in Cincinnati, Ohio, January 1865. Philadelphia: J. Gibbons, 1865.

The opposing forces exchanged volleys for about two hours, before a series of command errors threw the Canadians into confusion. The Fenians took advantage of it by launching a bayonet charge that broke the inexperienced Canadian ranks. Seven Canadians were killed on the battlefield, two died shortly afterwards from wounds, and four later died of wounds or disease while on service; ninety-four more were wounded or disabled by disease.Abstract of Names of Claimants for Pensions and Gratuities, Fenian Raid Service Records, Adjutant General's Office, United Canada, Pensions and Land Grants, RG9-I-C-5; Compensation of Injuries, Wounds, etc, Received on Active Service Fenian Raids 1866–1868 Volume 32, page 13, National Archives of Canada Ten Fenians were killed and sixteen wounded.

After the battle, the Canadians retreated to Port Colborne, at the Lake Erie end of the Welland Canal. The Fenians rested briefly at Ridgeway, before returning to Fort Erie. Another encounter, the Battle of Fort Erie, followed that saw several Canadians severely wounded and the surrender of a large group of local Canadian Militia who had moved into the Fenian rear. After considering the inability of reinforcements to cross the river and the approach of large numbers of Canadian Militia and British soldiers, the remaining Fenians released the Canadian prisoners and returned to Buffalo early in the morning of June 3. They were intercepted by the gunboat Michigan and surrendered to the United States Navy.

The traditional historical narrative alleges that the turning point in the Battle of Ridgeway was when Fenian cavalry was erroneously reported and the Canadian Militia ordered to form squares, the standard tactic for infantry to repel cavalry. When the mistake was recognized, an attempt was made to reform in column; being too close to the Fenian lines, it failed. In his 2011 history of Ridgeway, however, historian Peter Vronsky argues the explanation was not as simple as that. Prior to the formation of the square, confusion had already broken out when a unit of the Queen's Own Rifles mistook three arriving companies from the 13th Battalion (Canadian Militia) for British troops. When the Queen's Own Rifles began retiring to give the field to what they thought were British Army units, the 13th Battalion mistook this for a retreat and began withdrawing themselves. At this moment that the infamous "form square" order was given, completing the debacle that was unfolding on the field.Peter Vronsky, Ridgeway: The American Fenian Invasion and the 1866 Battle That Made Canada, Toronto: Penguin-Allen Lane, 2011. pp. 141–145.

A board of inquiry determined that allegations over the alleged misconduct of Lieutenant-Colonel Alfred Booker (13th Battalion), on whom command of Canadian volunteers had devolved, had "not the slightest foundation for the unfavourable imputations cast upon him in the public prints". Nevertheless, the charges dogged Booker for the rest of his life. A second board of inquiry into the battle at Fort Erie exonerated Lieutenant-Colonel J. Stoughton Dennis, Brigade Major of the Fifth Military District, although the President of the Board of Inquiry, Colonel George T. Denison, differed from his colleagues on several key points.

Five days after the start of the invasion, U. S. President Andrew Johnson issued a proclamation requiring enforcement of the neutrality laws, guaranteeing the Fenian invasion could not continue. Generals Ulysses S. Grant and George Meade went to Buffalo, New York to inspect the situation. Following instructions from Grant, Meade issued strict orders to prevent anyone from violating the border. Grant then proceeded to St. Louis. Meade, finding that the battles were over and the Fenian army interned in Buffalo, went to Ogdensburg, New York, to oversee the situation in the St. Lawrence River area. The U.S. Army was then instructed to seize all Fenian weapons and ammunition and prevent more border crossings. Further instructions on 7 June 1866 were to arrest anyone who appeared to be a Fenian.

Fenian commander Brigadier-General Thomas William Sweeny was arrested by the United States government for violating American neutrality. He was soon released and served in the United States Army until he retired in 1870.

Canada East