At first, most of the newly settled Normans kept household knights and did not settle their retainers with fiefs of their own, but gradually these household knights came to be granted lands of their own, a process known as subinfeudation. William also required his newly created magnates to contribute fixed quotas of knights towards not only military campaigns but also castle garrisons. This method of organising the military forces was a departure from the pre-Conquest English practice of basing military service on territorial units such as the hide.