either side of the limber pole. A driver rode on each left-hand ("near") horse and held reins for both the horse he rode and the horse to his right (the "off horse"). In addition to hauling the artillery piece, the limber also hauled the caisson, a two-wheeled cart that carried two extra ammunition chests, a spare wheel and extra limber pole slung beneath. There was one caisson for each artillery piece in a battery. The cannoneers could ride the ammunition chests on the limbers and the caisson when speed was required, but to do so for any length of time was too tiring for the horses, so cannoneers generally walked. The exception to this rule would be in horse-artillery batteries, where the cannoneers rode saddle horses. When the artillery piece was in action, the piece's limber would have been six yards behind the piece, depending on the terrain, with the caisson and its limber farther to the rear of the firing line, preferably behind some natural cover such as a ridge. While firing the piece, if possible, the crew kept the two ammunition chests on the caisson full, preferably supplying the gun from the third ammunition chest on the caisson's limber. When the ammunition from the ammunition chest on the piece's limber was exhausted, the piece's limber and the caisson's limber exchanged places. The empty ammunition chest was removed, and then the middle chest on the caisson was moved forward onto the limber. A fully loaded ammunition chest for a "Napoleon" 12-pounder weighed 650 pounds, so the chest was dragged and pushed, rather than lifted, into place. With a full ammunition chest in place, the limber was ready to move forward and supply the piece. Although the limber's primary purpose was to haul the artillery piece and the caisson, it also hauled the battery wagon and a traveling forge. The battery wagon carried spare parts, paint, etc., while the traveling forge was for use by a blacksmith in keeping the battery's hardware in repair. The ammunition chest on the limber hauling the battery wagon contained carpenters' and saddle-makers' tools, and the ammunition chest on the limber hauling the traveling forge contained blacksmiths' tools. Siege artillery limbers, unlike field artillery limbers, did not have an ammunition chest. Siege artillery limbers resembled their predecessors: they were two-wheeled carts with a pintle, now somewhat behind the axle. When the piece was to be