Saxony moved from a Prussian to French sphere in 1807, after Napoleon conquered Prussia. Saxony was a committed ally of France until the kingdom was overrun by coalition armies in 1813.
Saxon Gardes du Corps, coloured aquatint supposedly by or after Aster, 28.5 x 24.5 cm, 1806; source: Anne S.K. Brown Military Collection, Brown University Library, http://dl.lib.brown.edu/catalog/catalog.php?verb=render&id=1201277480515625.