Late medieval England was still a crusading country. The greatest military order after 1312, the Knights Hospitaller, also called the Order of St John of Jerusalem, held extensive English estates and supplied the crusading war effort with both money and manpower into the Tudor age. Their head, the Prior of St John, had his headquarters at Clerkenwell, just outside the city of London. This book focuses on the role of the Prior of St John in service to the crown between 1273 and 1540. Developments within both the crusading movement and England make this an appropriate starting point. In November 1272, Henry III of England died. The Lord Edward, at that time on crusade in the Holy Land, succeeded him, and appointed Joseph Chauncy, Hospitaller treasurer at Acre, as treasurer of England. Thus, a tangible link developed between the crusading movement and the realm of England, with the former offering service to the crown, and the latter promising support for future crusading campaigns. The later thirteenth century is also a suitable place to begin because the changes in the Prior's role in England can in part be explained by the perceived failings in the crusading movement that led to the loss of Acre in 1291. It is from 1295, for example, that the Prior started to receive regular summonses to parliament. A state of almost constant war from the 1290s with either Scotland or France also had a significant effect on the Prior's role. In 1540, the suppression of the English Priory took effect alongside the general dissolution of the religious houses.