A genealogical sketch of her is here. Her sister Charlotte was duchesse de Ventadour and her sister Marie Gabrielle was duchesse de la Ferté.
Upgrade image posted 4 August 2015 from bjws.blogspot.com/2015/07/17c-women-on-horseback.html; spots removed from background, the horse, and coiffure with Photoshop.
The duchesse d'Aumont appears to be wearing a sleeveless leather bodice in this Mignard portrait. Her dress does not show a military influence.
Keywords: Mignard, Françoise Angélique de La Mothe Houdancourt, duchesse d'Aumont, de La Mothe Houdancourt family, d'Aumont family, curly coiffure, hair jewelry, chemise, modesty piece, cuffs, criss-cross bodice, strap sleeves, under-bodice, elbow length puffed sleeves, lining, full skirt, shoes, robes, equestrian dress