Gideon (The Open University, UK) Brough 
The Rise and Fall of Owain Glyn Dwr [PDF ebook] 
England, France and the Welsh Rebellion in the Late Middle Ages

The subject of this compelling biography, Owain Glyn Dwr is one of the great figures of Welsh and military history. Initially a loyal subject of the king of England, he reluctantly took up arms against the Crown he had served. Once committed to rebellion, he proved surprisingly talented at leading rebel troops against a theoretically vastly superior enemy.
Gideon Brough reveals that Owain was more than just a warrior: he conceived and implemented a strategy which saw his small, poorly-equipped forces repeatedly defeat Crown troops and bring down the apparatus of governance in Wales. Following these achievements, he held native parliaments and established diplomatic contact with surrounding powers. This led to a treaty with France, after the conclusion of which, he welcomed French forces to Welsh soil to campaign with the rebels. In brief, Owain erected a rebel state and won international recognition, as the book soinsightfully shows. It later reflects on how Owain”s foreign support was fractured by the intrigues of exceptionally talented English diplomats at work in the French court and the subsequent creation of an environment which allowed Crown forces to concentrate on defeating the rebellion in Wales. Brough very effectively argues that, although ultimately unsuccessful, Owain emerges from the era as a gifted and honourable leader, giving the Welsh a figure commonly recalled as a hero.