Irish Republican Brotherhood
The Irish Republican Brotherhood, also commonly known as the IRB or the Fenians, was the largest and most influential of the nineteenth-century secret oath-bound societies in Ireland that were dedicated to ending British rule over Ireland by force and creating in its place an all-Ireland republican form of government completely independent of the British Empire. Their favourite weapons were terrorism and ambushes.
The IRA had substantial support among Irish emigrants in North America and in 1867 a group of them invaded Canada in sympathy with the IRB leaders in Ireland who staged an uprising against British rule in the same year. Its leaders were the chief organisers of the Easter Rising in Dublin in 1916, the event which the Irish poet W.B.Yeats, in his poem "Easter 1916" referred to as a 'terrible beauty'.