Complex sentence: When John became king, he chose to reign as an absolute monarch, notably never convening the Portuguese Cortes, the ancient parliament of the three estates in Portugal, and actively ignoring meetings of the Council of State.
Split into simpler sentences: When John became king, he chose to reign as an absolute monarch. Notably, he never convened the Portuguese Cortes, the ancient parliament of the three estates in Portugal, and actively ignored meetings of the Council of State.