To inform the consideration of The Inventory of Historic Battlefields in Wales, a phased programme of investigation was undertaken on the 1136 battle of Maes Gwenllian. Detailed reports of these investigations are available and comprise documentary and historical research (Border Archaeology), and non-invasive and invasive fieldwork (Archaeology Wales).

The battle of Maes Gwenllian should be viewed in the context of the breakdown of Anglo-Norman dominance across much of central and south Wales following the death of Henry I in December 1135. It also represents the only major battle in medieval Wales in which a woman is documented as having directly commanded one of the opposing armies. Gwenllian was the wife of Gruffydd ap Rhys, the Welsh prince of Deheubarth and daughter of Gruffydd ap Cynan prince of Gwynedd.

The only near contemporary account of the events of the battle is Gerald of Wales in his Itinerarium Kambriae , written some fifty years after the event:

Translation: We crossed the Loughor and the two Gwendraeth streams, and so came to Kidwelly Castle. It was in this region, after the death of Henry I, King of the English, and at a moment when her husband Gruffydd ap Rhys, Prince of South Wales, had gone to North Wales for reinforcements, that the Princess Gwenllian rode forward at the head of an army, like some second Penthesilea, Queen of the Amazons. She was beaten in battle by Maurice de Londres, who ruled over the district at that time and by Geoffrey the Bishop's constable. She was so sure of victory that she had brought her two sons with her. One of them, called Morgan, was killed and the other called Maelgwn was captured. Gwenllian herself had her head cut off, and so did many of her followers (Thorpe, 137).

The battle is traditionally reputed to be situated within an extensive area around Maes Gwenllian Farm (SN 4270 0867), situated some 2km north-east of Kidwelly Castle. The earliest definite reference found to the place name `Maes Gwenllian? occurs in a deed dated October 1432 (Border Archaeology). Metal detector survey in 2012 over part of this area revealed large amounts of modern ferrous objects as well as a reasonable amount of slightly older non-ferrous objects, but no finds contemporary with the battle (Archaeology Wales).

The RCAHMW inventory (1917, no. 156; NPRN 421808) makes reference to a low crescent shaped earthwork, on the north side of a field north-west of Maes Gwenllian Farm which is traditionally said to mark the burial place of Gwenllian and her son. This is no longer visible on the ground (Archaeology Wales).

A monument commemorating the battle is located outside the entrance to Kidwelly Castle (SN 4086 0697; NPRN 419373)

RCAHMW (Battlefields Inventory), Jan 2017

Bibliography
Archaeology Wales, 1136 Battle of Maes Gwenllian, Mynyddygarreg, Carmarthenshire: Battlefield Survey (2012).[/ref]
Border Archaeology, Maes Gwenllian (1136): Documentary and Historical Research Report (2009).[/ref]
Thorpe, Lewis (trans.), Gerald of Wales The Journey through Wales and The Description of Wales (Penguin, Harmondsworth, 1978).