Pedzisa mutsara unotevera: Muna April 1805, Saint-Germain akatumidzwa zita rokuti brigade general uye akapiwa mutungamiri muEtienne de Nansouty's 1st heavy cavalry division uye nokudaro akarwisa neGrande Armée munguva yeHondo yeChitatu yeChimwe uye
Hondo yeChipiri yeMubatanidzwa muna 1805-1806. A Baron weHumambo munaJanuary 1809, Saint-Germain akatungamirira brigade ye Nansouty's cuirassiers muhondo yeAspern-Essling uye akasimudzirwa kuva mukuru wechikamu muna July 1809. Muna 1812, akatora rutivi muHondo muRussia, achigamuchira ronda muhondo yeBorodino. MunaSeptember 1813, Saint-Germain akagadzwa kuva Count weHurumende uye akatora chikamu muhondo yeHanau, uko aive neruoko mukumanikidza kupfuura kwezvimedu zveGrande Armée kuenda kuFrance. Mukati mokurwisa kweFrance muna 1814, akatungamirira zviito zvinoverengeka zvevatasvi vemabhiza. Mukati meBourbon Restoration akafamba zvakanaka uye muna 1818 akatumidzwa kuti Inspector general of cavalry.