 As the need for such service functions became more acute (as, for example, during the Investiture Controversy), and their duties and privileges, at first nebulous, became more clearly defined, the "ministeriales" developed in the Salian period (1024–1125) into a new and much differentiated class.They received fiefs, which to begin with were not heritable, in return for which they provided knightly services.They were also allowed to possess, and often did hold, allods