1233: "That year there was strife between king Henry and Richard Marshal, earl of Pembroke. And then the earl made a pact with Llywelyn ap Iorwerth and with the princes of Wales. And forthwith he and Owain ap Gruffudd gathered a mighty host; and they attacked Monmouth and burned it and made a slaughter of the king's men who were there defending."
Source: Thomas Jones, The Chronicle of the Princes, 1955, p.231.
Earl Richard of Pembroke, supported by Llywelyn ap Iorwerth, defeated John of Monmouth in a pitched battle near Monmouth on 26 December 1233.
Source: J.E.Lloyd, A History of Wales, vol II, 1912, p.679.
Other sources, as yet unverified, suggest that the attack on Monmouth took place on 25 November, 26 December or both.
Glamorgan-Gwent Archaeological Trust records refer to the battle as "Castle Field, Monmouth" (no.03132g) and give a National Grid Reference of SO 5014 1318, on the west side of ther river Monnow and some 500m northwest of the town.
B.A.Malaws, RCAHMW, 09 October 2006.