In the following passage from Alter-Nations, Martin places Fenianism with the contexts of the British Empire and resistance to it. — George P. Landow.
Fenianism combined various, seemingly opposed forms of anticolonial strategy: the revolutionary advocation of 'physical force' and preparation for militarized resistance; nonviolent forms of activism; republican gestures such as the creation of an Irish currency; the publication of nationalist writing; and serious engagement with other radical movements, including anticolonial insurgents throughout the British Empire/Marx describes the movement as possessing a variety of characteristics that distinguished it from previous forms of Irish anticolonialism and nationalism: it was lower-class, even socialist, in its composition; it was not Catholic but secular; it did not have a representative in the British Parliament; and it possessed multiple fields of action (Ireland, America, England, and other sites throughout the Empire) and could therefore be described as a global or internationalist movement.
Joyce was interested in radical Fenianism for many of the same reasons as Marx. He recounts with admiration Fenianism's ability to marshal mass support in Ireland. He also describes in detail the secret, oath-bound movement's cellular structure, a mode of organization derived from French and Italian revolutionary societies as well as Irish agrarian subaltern movements: "[T]he country was organized into circles composed of a Sergeant and twenty five men," he writes, "a vast and intricate net, whose threads were in Stephens' hands. At the same time, the American Fenians were organized in the same way, and the two movements worked in concert. Among the Fenians there were many soldiers in the English Army, police spies, prison guards, and jailers. Everything seemed to go well, and the Republic was on the point of being established" (CWL89). He identifies this radically decentralized, opaque cell structure as the ideal defense against informers and betrayal, a particular obsession of Joyce in his political writings and the primary tactics used by the British state in its transforming strategies of counterinsurgency. 
Martin, Amy E. Alter-Nations: Nationalisms, Terror, and the State in Nineteenth-century Britain and Ireland. Columbus: Ohio State University Press, 2012. [review in the Victorian Web].
Last modified 26 May 2013