By the turn of the 19th century, breeches, pantaloons and trousers worn by all men were sewn with a flap in front called a fall front. This flap was universally held in place by two or three buttons at the top. No belts were worn. Instead, breeches, pantaloons and trousers were held up by tight-fitting waists, which were adjusted by gusset ties in back of the waist. Seats were baggy to allow a man to rise comfortably from a sitting position. As waists rose to the belly button after 1810, suspenders were used to hold the garment up.
Jane Austen's World Blog - by Vic