In April 1264 an encounter took place, as part of the Baron's War wherein Henry III of England besieged Simon de Montfort's supporters who were holed in at Northampton Castle. De Montfort mounted a rear-guard rescue attempt but on April 61264 the castle fell and De Montfort's son (another Simon) was captured by the King's forces.
References
R. F. Treharne. The battle of Northampton, 5th April 1264. In: Simon De Montfort and Baronial Reform: Thirteenth-Century Essays. R. F. Treharne, E. B. Fryde (editors). Hambledon Press, London, 1986. ISBN:0907628702; pp. 299-303