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 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.

Irish republicanism is the political movement for the unity and independence of Ireland under a republic. Irish republicans view British rule in any part of Ireland as inherently illegitimate. An ideology since the 17th century, various methods have been employed to achieve the republic, including rebellions and paramilitary campaigns. Although the makeup of republicanism has been multidenominational, its relation to catholicism increasingly became central.