It is interesting to note that the American Artillery Units have all horses both saddled and harnessed, to pull the guns, though only the left side horses are carrying their Postillion riders. Riders lead the right side horse with his bridle reins. None of the horses wear blinker bridles. Horses carry no supplies on their backs. This was so that if needed, any gun horse could be ridden by the gun crew to escape capture if the gun was over run or taken for ridden use by an Officer. You can still see this style of saddle/harness on the Old Guard horses who do the pulling of the Caissons at Arlington Cemetery for the funerals.
The UK King’s Troop Artillery, do not saddle the horses on the right side of the hitch. Only the horses ridden by the Trooper are saddled, while the right hand horse is held by his bridle reins and kept even with the left side horse in each position of the hitch. Trooper wears a steel brace on his right boot, to prevent leg being crushed by the other horse.
The guns are NEVER fired when the horses are hitched to them. Horses are removed from the guns and ridden a distance away, before firing would commence. Horses and Troopers are expected to stand ready to return to the guns if signaled, for quick gun attachment and moving to a new location during battle. There are NO BRAKES on these guns or caissons, so horses moving fast, accurately, are the only thing controlling the stopping.