James StephensThe Irish Republican Brotherhood (IRB) was a secret organization founded in Dublin in 1858 by James Stephens (1824–1901) to secure the creation of an independent Irish republic. It was closely linked with the Fenian Brotherhood in the USA and its members came to be called Fenians. The primary object of the IRB was to organize an uprising in Ireland; the Fenian Brotherhood worked to support the IRB with men, funds, and a secure base. The British government acted swiftly; IRB leaders including Stephens were arrested.

The 1867 Fenian Rising, led by Thomas Kelly, was a failure. The Home Rule League, the Land League, the Irish Volunteers, and Sinn Fein often appeared to supersede the IRB as political forces; but Fenians were active in all these organizations. The Home Rule Bills failed to satisfy them and in World War I the IRB, led by Pádraic Pearse, sought German help for the abortive Easter Rising. The IRB was subsequently superseded by the Irish Republican Army.