Valise porte-manteau
Valise porte-manteau (Fr.; Ger. Mantelsack), cylindrical or square container made of leather or cloth, which opens with a flap on the long side. The valise is strapped onto the back of the horse, behind the saddle, in order to carry all sorts of things needed on the journey. In the cavalry, the valise is one of the uniform items, and is usually made of the same cloth as the rider‘s coat. Cf. Valise.
Source: Pierer’s Universal-Lexikon 4. Auflage 1857–1865
Valise porte-manteau, container for travel utensils; Formerly used by mounted troops to carry clothing and strapped to the back of the saddle.
Source: Meyers Großes Konversations-Lexikon, 6. Auflage 1905–1909