The Fenian raids of the Fenian Brotherhood based in the United States on British army forts, customs posts and other targets in Canada were fought in order to bring pressure on Britain to withdraw from Ireland, between 1866 and 1871. They divided many Catholic Irish-Canadians, many of whom were torn between loyalty to their new home and sympathy for the aims of the Fenians. The Protestant Irish were generally loyal to Britain and fought with the Orange Order against the Fenians. While the U.S. authorities arrested the men and confiscated their arms afterwards, there is speculation that many in government had turned a blind eye to the preparations for the invasion, angered at actions that could be construed as British assistance to the Confederacy during the American Civil War. There were five Fenian raids of note.

Campobello Island Raid (1866):

This Fenian raid occurred in April, 1866, at Campobello Island, New Brunswick. A Fenian Brotherhood war party of over 700 members arrived at the Maine shore opposite the island with the intention of seizing Campobello from the British. The U.S. government intervened and a military force dispersed the invaders. This action served to reinforce the idea of protection for New Brunswick by joining with the British North American colonies of Nova Scotia, and the United Province of Canada, formerly Upper Canada (now Ontario) and Lower Canada (Quebec) in Confederation to form the Dominion of Canada.
Niagara Raid (Battles of Ridgeway and Fort Erie) (1866)

In 1866, the Fenians had split into two factions, with the original faction, led by Fenian founder John O'Mahony focused more on fundraising for rebels in Ireland. The leaders of 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 an April attempt to raid New Brunswick (see "Campobello Island Raid", above) that had been blessed by O'Mahony failed, the senate faction Fenians implemented their own plan for an invasion of Canada. The plan drafted by the senate "Secretary for War" General T. W. Sweeny, a distinguished former Union Army officer, called for multiple Fenian invasions at points in Canada West (now southern Ontario) and Canada East (now Quebec) intended to cut Canada West off from Canada East and possible British reinforcements arriving from there. 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 would be the only Fenian attack, other than the Quebec raid several days later, that would be actually launched in June 1866.

Approximately 1000 to 1,300 Fenians crossed the Niagara River in the first 14 hours of June 1 under Colonel John O'Neill. Sabotaged by Fenians on its crew, the U.S. Navy's side-wheeler gunboat USS Michigan did not begin intercepting Fenian reinforcements until 2:15 P.M.--fourteen hours after Owen Starr's advance party had first crossed the river in advance of O'Neill's main force. Once the USS Michigan was deployed, O'Neill's force in the Niagara Region was cut off from supplies and reinforcements consisting of several hundred (Canadian sources claim up to 3,000) Fenian insurgents.
O'Neill's Fenian soldiers called themselves the "Irish Republican Army," and some wore uniforms with "IRA" buttons. This is considered to be the first use of the term. (A well-known painting of the battle in the National Archives of Canada depicts a green flag with the letters IRA over a gold harp; in fact, the most common Fenian emblem at this time was a sunburst.)

After assembling with other units from the province and travelling all night, the Canadians advanced into a well-laid ambush (Battle of Ridgeway) by approximately 300 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. The Canadian militia consisted of inexperienced volunteers with no more than basic drill training and primarily Enfield rifled muskets comparable to the armaments of the Fenians. A single company of the Queen's Own Rifles had been armed the day before on their ferry crossing from Toronto with Spencer repeating rifles, and had never been given the opportunity to practice with them. The Fenian forces were mostly battle-hardened American Civil War veterans, armed with weapons procured from leftover war munitions, also Enfield rifled muskets or the comparable Springfield.

The Canadians retreated in broken ranks, abandoning their dead and wounded on the battlefield and in farm houses in the vicinity, while the Fenians celebrated the first Irish victory over British forces since the Battle of Duncairn in 1798. Thirty one Canadians had been killed on the battlefield, two died from wounds sustained, and four would later die of disease while on service and ninety-four were wounded or disabled by disease.

After the first clash, the Canadians retreated to Port Colborne at the Lake Erie end of the Welland Canal, while the Fenians rested at Ridgeway briefly before themselves returning to Fort Erie. Another fight followed there that saw the surrender of another large group of local Canadian militia that had moved into the Fenian rear. But after considering the inability of reinforcements to cross the river and the approach of large numbers of both militia and British regulars, the remaining Fenians chose to return to Buffalo. They were intercepted by the Michigan, and surrendered to American naval personnel.

Some later accounts attribute the conduct of Canadian forces to being "cowardly, un-patriotic, and treasonous" and make allegations of vastly inferior forces on the part of the Fenians. Hardware had by both sides was comparable. The turning point in the battle was when Fenian cavalry was erroneously reported and the command was given to form square, the tactic at the time for infantry to repel cavalry. When the mistake was recognized, an attempt was made to reform column but being far too close to the Fenian lines, attempts to reform were hopeless. It is telling that a formal board of inquiry into the conduct of Canadian defenses exonerated Lt. 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 some key points. Regarding allegations to the misconduct of Lt. Colonel Albert Booker (13th Btn.), upon whom command of Canadian volunteers had devolved, was determined by the same Board of Inquiry to have "not the slightest foundation for the unfavourable imputations cast upon him in the public prints". These allegations dogged Booker for the rest of his life.

President Andrew Johnson's proclamation requiring enforcement of the laws of neutrality was issued five days after the beginning of the invasion, guaranteeing that it would not continue. Both US General Ulysses S. Grant and U.S. General George Meade went to Buffalo, New York to assess the situation. In the meantime, following instructions from General Grant, General Meade issued strict orders to prevent anyone from further violating the border. General Grant then proceeded to St. Louis while General Meade, finding that the battle at Ridgeway was over and the Fenian army interned in Buffalo, proceeded to Ogdensburg, New York to oversee the situation in the St. Lawrence River area. The US Army was then instructed to seize Fenian weapons and ammunition, and to prevent more border crossings. Further instructions on 7 June 1866 were to arrest anyone who looked like they might be a Fenian.

Ironically, although they did not do much to advance the cause of Irish independence, the 1866 raids and the inept efforts of Canadian colonial troops to repulse them helped to galvanize support for the Confederation of Canada in 1867. Some historians have argued that the debacle tipped the final votes of reluctant Maritime provinces in favour of the collective security of nationhood, making Ridgeway the "battle that made Canada."

In June 2006 the Ontario's heritage agency dedicated a plaque at Ridgeway on the commemoration of the 140th anniversary of the battle. Many members of today's Canadian army regiment, The Queen's Own Rifles of Canada, return to the Ridgeway battle site each year on the weekend closest to the June 2nd anniversary for a bicycle tour of the battle sites.

Alexander Muir, a Scottish immigrant, author of the former Canadian anthem "The Maple Leaf Forever" and member of the Orange Order, fought at Ridgeway with the Queen's Own Rifles.

A Fenian commander was Brigadier General Thomas William Sweeny who was arrested by the United States government for his involvement; however, he later served in the Regular Army until his retirement in 1870.

Pigeon Hill Raid (1866):

This Fenian raid occurred on June 7, 1866, at Pigeon Hill.

Mississquoi County Raid (1870):

This Fenian raid occurred during 1870 and the Canadians, acting on information supplied by Thomas Billis Beach, were able to wait for and turn back the attack.
Pembina Raid (1871)
Fenian John O'Neill, after the failed 1870 Fenian invasion of Canada, had resigned the Senate Wing then joined the Savage Wing. In return he was given a seat on the Savage Wing governing council. In 1871 O'Neill and an odd character named W. B. O'Donoghue asked the Savage Wing Council to undertake another invasion of Canada across the North Dakota border. The Council, weary of Canadian adventures in general and O'Neill in particular, would have none of it. O'Neill's idea was turned down, but the Council promised to loan him arms and agreed they would not publicly denounce him and his raid. O'Neill resigned from the Fenians in order to lead the invasion, which was planned in Saint Paul, Minnesota to invade Manitoba near Winnipeg, Canada. Around 35 men, led by John O'Neill, William B. O'Donoghue, and John J Donnelly had hopes of meeting up with Louis Riel's French-Indian Métis. The O'Neill led force managed to capture a Hudson's Bay Company post just north of the international border on 5 October. O'Neill, J J Donnelly and ten more men were taken prisoner by U.S. soldiers under Capt. Lloyd Wheaton near Pembina, North Dakota. The raid was doomed from the start: it took place inside US Territory, and the Métis under Riel signed a pact with the British just as the invasion was beginning. Riel and his Métis subsequently captured O'Donoghue and turned him over to the US Government. In a rather muddled Federal response, O'Neill was arrested twice, once in Dakota and once in Minnesota, but released and never charged. The 10 men captured with O'Neil were released by the court as "dupes" of O'Neill and Donnelly.

Agitation in Pacific Northwest:
The Fenian Brotherhood organized openly in the Pacific Northwest states during the 1870s and 1880s, agitating to invade British Columbia. Although no raids were ever launched, tensions were sufficient that the British posted a number of large warships to the new railhead at Vancouver, British Columbia for the celebrations opening the Canadian Pacific Railway in 1886.

Results and long term effects:

Support for the Fenian Brotherhood's invasion of Canada leveled out and there was no real threat of any more raids after the 1890s. The raids, however, did have a large effect on Canada-U.S. relations for years after the last raid.

There was a great deal of anger in Canada with the U.S. government, who Canadians felt had looked the other way and failed to prevent the raids on their end. There is even some indication that U.S. President Andrew Johnson may have given his blessing to the early raids, saying that he would "recognize the accomplished facts," implying that if the Fenians were successful, he would support them.

Canada-U.S. relations, which had been improving in the decades leading up to the Civil War, remained strained until Anglo-American rapprochement in the first decade of the 20th century. However, though relations markedly improved after this period, Canadian-American relations remained considerably distant until co-operation during the Second World War.

We are the Fenian Brotherhood, skilled in the arts of war, And we're going to fight for Ireland, the land we adore, Many battles we have won, along with the boys in blue, And we'll go and capture Canada, for we've nothing else to do. -- Fenian soldier's song