WALES A horse brass is a brass plaque used for the decoration of horse harness gear Features 2 brass pieces of flat brass with hanger by which the brass is threaded onto a horse harness strap, known as a Martingale. By the late 19th century horses were decorated with brasses of all kinds and sizes. During this era working horse parades were popular throughout the British Isles and prize or merit awards were given. Vintage, Early to Mid 20th Century England dry and cracked leather; scratches and surface marks; finish loss; oxidation; verdigris; residue.