Complex sentence: A major institutional change from previous practice was introduced in 1585 when the main executive functions of Holland started to be carried out by the "Gecommitteerde Raden", usually translated as "Delegated Councillors".
Split into simpler sentences: A major institutional change from previous practice was introduced in 1585. The main executive functions of Holland were carried out by the "Gecommitteerde Raden", usually translated as "Delegated Councillors".