Complex sentence: The original Biedermeier period changed with the political unrests of 1845-1848 (its end date) with the revolutions in European historicism and furniture of the later years of the period took on a distinct Wilhelminian or Victorian style.
Split into simpler sentences: The original Biedermeier period changed with the political unrests of 1845-1848 (its end date). With the revolutions in European historicism, furniture of the later years of the period took on a distinct Wilhelminian or Victorian style.