In The Irish Republican Brotherhood 1914-1924, John O’Beirne Ranelagh provides a well-sourced description of the landscape (and dynamics) of Irish Republicanism during a critical period for the country.
The apparent level of access O’Beirne Ranelagh to key IRB and IRA players, in addition to his own family history in the movement, allowed him to describe events of the IRB as a secret organization at a level beyond efforts of previous authors.
This book does not romanticize the Republican movement, instead focusing on the IRB structure as it relates to other Republican organizations (GAA, Gaelic League, the Volunteers/IRA) and with the Dáil. It is invaluable in its contributions to the understanding of Republicanism at the time.
The book itself provides comprehensive end notes containing citations and, importantly, additional context.