To inform the consideration of `The Inventory of Historic Battlefields in Wales', documentary and historical research was commissioned on the 1282 Bridge of Boats battle and the resulting research report provides a detailed overview (Chapman).

The Bridge of Boats was a pontoon bridge from Anglesey, where King Edward I had established a base, and was intended to secure a bridgehead on the mainland for Edward's final phase of invasion and conquest of Gwynedd. Edward's forces led by Luke de Tany found themselves stranded due to the turning tide on the shore of the mainland where they were either drowned in their attempts to escape or slaughtered by Welsh forces as noted in the Peniarth MS.20 version of the Brut y Tywysogyon :

Ac a vanassant goresgin arvon ac ena y gwanaeth pwyd y bont ar venei ac y torres y bont o tra llwith ac y bodes aneirif or season ac ereill a las (Jones, 228)

Translation: And they desired to gain possession of Arfon. And then was made a bridge over the Menai; but the bridge broke under an excessive load, and countless numbers of the English were drowned and others were slain (Jones, 120)

This marked the most significant reversal suffered by the English in Edward I's final war of conquest against Llywelyn ap Gruffudd in 1282.

The misleading traditional name for this encounter has been the `Battle of Moel y Don', SH 5183 6777 a point on the Anglesey shore where the straits narrow to a point that was used as a ferry crossing throughout the Middle Ages. Recent re-examination suggests that the bridge was constructed further north and nearer to Edward's centre of operations at Llanfaes on Anglesey. Two suggestions have been made, a site close to Llanfaes extending to the mainland near Abergwyngregyn near the sandbank of Traeth Lafan (SH 634 750) or close to Bangor (SH 582 735) where a fortified bridgehead was subsequently established at the second attempt.

RCAHMW (Battlefields Inventory), Jan 2017

Bibliography
Chapman, A., Bridge of Boats 6 November 1282: Documentary and Historical Research Report (2013).
Jones, Thomas (gol.), Brut y Tywysogyon: Peniarth MS. 20 (Caerdydd, Gwasg Prifysgol, Cymru, 1941).
Jones, Thomas (trans.), Brut y Tywysogyon or The Chronicle of the Princes Peniarth MS. 20 Version (Cardiff, University of Wales Press, 1952).