[1] D'Ornano served in Italy during the French Revolutionary Wars (in 1798 and 1799), and later took part in the Saint-Domingue expedition.

He commanded the 5th Dragoon regiment during the Battle of Fuentes de Oñoro, after a brave attack of cavalry, he was promoted to brigadier general.

He returned to France and resumed active service in 1829 when he was given a position at the Military Academy of Saint-Cyr.

In 1816, d'Ornano married his longtime lover, Countess Marie Walewska (née Łączyńska), the former wife of Count Athenasius Colonna-Walewski, whom she divorced in 1812.

After their marriage, they settled in Liège as d'Ornano did not want to return to Paris due to his pro-Napoleonic allegiances.

After the death of his wife, her heart was placed in the crypt of the d'Ornano family at Père Lachaise Cemetery in Paris and her body was brought back to Poland for burial.