In England, knighthood was always regarded as the necessary distinction of people of some substance and estate.[384] In the reigns of our three first Edwards the qualification for knighthood varied from land of the yearly value of forty to that of fifty pounds. The King was the sovereign and supreme judge of chivalry, and he might confer knighthood on whomsoever he chose. He could compel men of worth to be knights, for knighthood was honourable to the kingdom. Like the performance of every other duty in all states of society, that of knighthood could be commuted for by money; and the royal invitation to honour was so extensive as to be inconvenient; for a statute was passed in the reign of Edward II. whereby the King respited for some time the payment of the fines of such persons whose station in the world made knighthood a necessary part of their consequence. Besides all these ways of forming the knighthood of England, must be added the custom of elevating to chivalric dignities men who had gained renown by martial exploits. This was indeed a mode more pure in principle, and, therefore, more honourable than any we have mentioned. The military necessities of many of our sovereigns favoured the growth of chivalry. William Rufus invited to his court the prowest cavaliers from every country[385]; for as his father had effected the subjugation of Harold not merely by the feudal force of Normandy, but by hired soldiers, it was the natural policy of the kings of the Norman line to attach to their person valiant men who were not connected by ties of nature with the people. [Sidenote: Fine instance of chivalry in reign of Henry I.]