Complex sentence: From 28 November 1857 onwards, Willmar was a member of the newly founded Council of State, and remained as such until his death on 26 November 1866 in Luxembourg city.
Split into simpler sentences: From 28 November 1857 onwards, Willmar was a member of the newly founded Council of State. This he remained until his death on 26 November 1866 in Luxembourg city.