The Fenian Invasion of Canada

May 31, 1866:

In the Fenian Invasion of Canada, John O'Neill leads 850 Fenian raiders across the Niagara River at Buffalo, New York/Fort Erie, Ontario, as part of an effort to free Ireland from the United Kingdom. Canadian militia and British regulars repulse the invaders in over the next three days, at a cost of 9 dead and 38 wounded to the Fenian's 19 dead and about 17 wounded.

Between 1866 and 1871, the Fenian raids of the Fenian Brotherhood, who were based in the United States, on British army forts, customs posts and other targets in Canada, were fought to bring pressure on Britain to withdraw from Ireland. 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 the U.S. 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.
In 1866, the Fenians had split into two factions, with the original faction, led by Fenian founders James Stephens and 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 southern 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 further supplies and reinforcements.

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 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.)

It is one of the stranger attempts to get the English out of Ireland.