This book comprises of a re-publication of Thomas Matthew's 1910 edition of Welsh documents held in the Archives Nationale of France, together with new introductions to the original work and to its editor. The aim is to make the documents, from the Medieval period relating to Llewelyn Fawr, the Bishop of Menevia and Owain Glyndwr, available to a new audience; to consider them from a contemporary perspective; to update and revise Matthew's original evaluation, and to note recent developments in scholarship in this area. In addition the book will examine the life, work and contribution of Thomas Matthews to Welsh culture through exploration of his Pan-Celtic links and though his contribution to education, Welsh literature and the Arts.