If the medieval king was the helmsman of the ship of state, the royal household was the ship’s engine. It comprised men from most ranks of society, from the great magnates of the realm to simple servants who looked after the day-to-day needs of the king and his court. English government, in both peace and war, was conducted through the royal household, amongst whom the most important men were the king’s knights: socially elite, militarily pre-eminent, and indispensable for the workings of English medieval government. It is with these men during the reign of King John that this work is concerned.