The Irish Republican Brotherhood (IRB) The Irish Republican Brotherhood (IRB) was a small, secret, revolutionary body (known as the Fenian movement in the 1850s and 60s), committed to the use of force to establish an independent Irish republic. It was rejuvenated, between 1910-12. Read more here: http://www.bbc.co.uk/history/british/easterrising/profiles/po17.shtml
Michael Collins was the last President of the Irish Republican Brotherhood prior to Independence although the organisation was no longer the force it had been in the 19th century particularly after the emergence of the IRA and Sinn Fein. His use of the IRB to pass the treaty was resented by many.
April 24, 1916: Easter Rebellion begins.On this day in 1916, on Easter Monday in Dublin, the Irish Republican Brotherhood, a secret organization of Irish nationalists led by Patrick Pearse, launches the so-called Easter Rebellion, an armed uprising against British rule.