To inform the consideration of The Inventory of Historic Battlefields in Wales, a phased programme of investigation was undertaken on the battle of Craig y Dorth. Detailed reports of these investigations are available and comprise documentary and historical research (Border Archaeology), and non-invasive and invasive fieldwork (Archaeology Wales).

The only source to refer specifically to the battle is The Annals of Owain Glynd'r :

'Yn yr vn flwyddyn hono I bv y lladdfa ar Gymrv ar vynydd Kamstwn, a'r llall ar y Saesson ar Graic y Dorth rrwn Pen y clawdd a Thref Vynwy. Yno y llas y Saesson gan mwyaf oll ac I bv y dilyn arnynt hyd a mhorth y dref' (Livingston and Bollard, 175).

Translation: 'In that same year there was a slaughter of the Welsh on Campston Hill and another of the English on Craig-y-dorth, between Pen-y-Clawdd and Monmouth town. There the English were killed for the most part, and they were pursued up to the gates of the town' (Livingston and Bollard, 175).

The site of the battle has been traditionally located at Craig y Dorth, a promontory forming a spur of the Trellech range. `Site of Battle A.D. 1404? is marked on the first to fourth edition Ordnance Survey maps at SO 4832 0895. Recent fieldwork in this area did not find evidence that could definitively be linked to the battle (Archaeology Wales).

RCAHMW (Battlefields Inventory), Nov 2016

Bibliography
Archaeology Wales, 1404 Battle of Craig y Dorth: Battlefield Survey (2014).
Border Archaeology, Craig y Dorth (1404): Documentary and Historical Research Report (2009).
Livingston, Michael and Bollard, John K. (eds) Owain Glynd'r A Casebook (Liverpool University Press, 2013).