This page leads to a number of essays outlining the history of the O’Byrnes of Leinster and their early branches.
It also gives brief outlines of the histories of the other clans who bear the surname Byrne or a similar varient.
Cover of the ‘O’Tooles of Feracualan’, a 19th century work by ‘John O’Toole’. However, ‘John O’Toole’ was really Fr. Meehan, a curate in Rathdrum, Co. Wicklow, and the book is far more O’Byrne of Leinster history than O’Toole history. Just a fragment in the complexity of researching the surname Byrne.