This dissertation is the first in-depth study of the medieval Irish corpus of ‘Three Men and the Dog of Irúath’. This story survives in different forms (poetry and prosimetrum) in manuscripts ranging in date from the twelfth to the nineteenth century. The present study focusses primarily on the poem ‘Dámh trír tháncatar illé’ ‘A company of three men came here’, the earliest surviving version of this story, and the prosimetric embedded tales found as part of Acallam na Senórach ‘The Colloquy of the Ancients’, which offer a similar version with a different ending.

Chapter I presents a detailed study of ‘Dámh trír tháncatar illé’. I examine the earliest extant version of the poem found in Dublin, Trinity College 1339, The Book of Leinster (s. xii), and argue that the poem should be considered part of Scribe A’s collection of dindshenchas texts. I then discuss the version of the poem found in Cork, University College 204, The Book of Lismore (s. xv), as part of Agallamh Bheag ‘The Small Colloquy’ (AB), and present a scholarly edition of the poem and its prose introduction from AB in the Book of Lismore.

Chapter II focusses on the embedded tales about the three men and the dog of Irúath in Acallam na Senórach (AS). I analyse the physical evidence of the manuscripts of AS and demonstrate that scribes engaged with the structure of the text using colours, paragraphs and enlarged letters. A scholarly edition of the prosimetric embedded tales is presented, based on Oxford, Bodleian Library, Laud Misc. 610 (s. xv) and Dublin, University College Franciscan A 4 (s. xv–xvi), and including significant variants from the other manuscript witnesses in the apparatus criticus.

Further insights into the textual tradition of ‘Three Men’ are offered in Chapter III. First, I offer a study of the figure of the dog of Irúath across medieval Irish literature, evidencing the creative mindset of medieval Irish scribes in making intertextual connections between texts. Then, I analyse the narratological structure of the embedded tales in AS and show how metanarration, mise en abyme and narratorial illusionism are used in the text. Finally, I return to the intertwining of fíanaigecht and dindshenchas and I demonstrate that dindshenchas is used as a structural and compilatory tool in AS and AB, offering evidence that AB was compiled using AS.

This thesis thus makes significant progress in our understanding of the textual complexity of ‘Three Men and the Dog of Irúath’, AS and AB, and offers a framework for further studies into the creative compilatory practices of the medieval Irish literati.