Complex sentence: The colony's charter called for a governor, deputy governor, and 18 assistant magistrates (who served as a precursor to the idea of a Governor's Council), who were all to be elected annually by the freemen of the colony.
Split into simpler sentences: The colony's charter called for a governor, deputy governor, and 18 assistant magistrates who served as a precursor to the idea of a Governor's Council. All these officers were to be elected annually by the freemen of the colony.