The Fenian raids of the Fenian Brotherhood, an Irish Republican organization 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 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, there is speculation that some in the U.S. government had turned a blind eye to the preparations for the invasion, angered at actions that could have been construed as Canadian assistance to the Confederate States of America during the American Civil War. There were five Fenian raids of note and all of them ended in failure.
- April 1866; Campobello Island Raid
- June 1866; Niagara Raid (Battle of Ridgeway and Battle of Fort Erie)
- June 1866; Pigeon Hill Raid
- May 1870; Missisquoi County Raid (Battle of Eccles Hill)
- October 1871; Pembina Raid