The period discussed in this book was one of significant change in the nature of military service in both England and Wales. The conquest of Wales by Edward I completed a process of expansion by the English Crown into Wales which had lasted centuries. It also marked the beginning of the end of another process, the transition from armies with a feudal component that held land in return for military service to armies recruited by various methods in return for pay. The settlement imposed upon Edward's newly conquered territories in Gwynedd – the statutes of Rhuddlan of 1284 – imposed legal and administrative conditions upon the Welsh. In common with similar provisions in England, they also imposed conditions upon men to serve in arms against the king's enemies. This chapter and that which follows will consider the theoretical implications of this settlement: military obligation in law and custom, and then their practical application in the practices and processes of recruitment, payment and deployment.

The nature of military obligation, as it existed in the English realm in the late thirteenth and early fourteenth centuries, was in flux. English kings had long found the apparently simple demands of the feudal summons a severe constraint on their ability to wage war. For this reason they had employed mercenaries and sought ways around its restrictions since at least the early twelfth century. Welshmen, paid for their service were often part of the solution. Edward I's Welsh wars changed the state of military obligation in England. The duty of all free men in England to possess the arms and military equipment appropriate to their status and wealth had been set out by Henry II in the Assize of Arms in 1181. In their laws, the Welsh princes invoked similar obligations, although these were not generally tied to land until Llywelyn ab Iorwerth made attempts to establish a military elite based on tenure of land in the thirteenth century. In November 1282 all free men with at least twenty liberates of land who were not serving in the Welsh war were summoned to appear at Northampton early in the next year, together with shire and borough representatives. Edward's objective was doubtless to secure financial grants in return for the service they were not doing. If so, he was unsuccessful and the obligation of military service inherent in the summons was not recognised.