O'Rahilly was not party to the plans for the Easter Rising, nor was he a member of the Irish Republican Brotherhood (IRB), but he was one of the main people who trained the Irish Volunteers for the coming fight. The planners of the Rising went to great lengths to prevent those leaders of the Volunteers who were opposed to unprovoked, unilateral action from learning that a rising was imminent, including its Chief-of-Staff Eoin MacNeill, Bulmer Hobson, and O'Rahilly. When Hobson discovered that an insurrection was planned, he was kidnapped by the Military Council leadership.