Empress Eugénie and the Ladies are dressed in day dress while the men are in business suits for this 1861 diplomatic event portrayed by Maurand. The snappy uniforms are worn by the guards on the stairs.
This is ironic from the 21st century perspective. The King could be Frederick William IV (1795 - 1861) or Wilhelm I (1797 - 1888). Wilhelm I defeated Napoleon III's France and was proclaimed Kaiser of Germany - in Versailles. This act of arrogance helped set in motion events, largely driven by urges for revanche prior to 1914 and vergeltung after 1919 (Fr. and Ger., respectively for vengeance), leading to World Wars I and II.