This study aims to supply the first contextually precise account of the male gender anxieties and ambivalences haunting the culture of Irish nationalism in the period between the Act of Union and the founding of the Irish Free State. To this end, Joseph Valente focuses upon the Victorian ethos of manliness or manhood, the specific moral and political logic of which proved crucial to both the translation of British rule into British hegemony and the expression of Irish rebellion as Irish psychomachia. The influential operation of this ideological construct is traced through a wide variety of contexts, including the career of Ireland’s dominant Parliamentary leader, Charles Stewart Parnell; the institutions of Irish Revivalism–cultural, educational, journalistic, and literary; the writings of both canonical authors (Yeats, Synge, Gregory, and Joyce) and subcanonical authors (James Stephens, Patrick Pearse, Lennox Robinson); and major political movements of the time, including suffragism, Sinn Fein, Na Fianna E Eireann, and the Volunteers. The construct of manliness remains very much alive today, underpinning the neo-imperialist marriage of ruthless aggression and the sanctities of duty, honor, and sacrifice. Mapping its earlier colonial and postcolonial formations can help us to understand its continuing geopolitical appeal and danger.