Complex sentence: He pressed publicly for greater reform of government, taking the side of the Opposition against his colleagues and the King, until he was replaced by the Viscount Osborne, soon to be Earl of Danby, in the summer of 1673.
Split into simpler sentences: He pressed publicly for greater reform of government, taking the side of the Opposition against his colleagues and the King. Shaftesbury was replaced by Viscount Osborne, soon to become Earl of Danby, in the summer of 1673.