Precautions: Make sure your horse is obedient to your aids and that you can maneuver him laterally as well as stop and start in any gait with a snaffle bit. To give your horse every advantage if he is sensitive, put cotton in his ears (down deep). If you have the facilities feed him in a confined area while you play loud battle sounds on a tape or CD player in the barn, the Gettysburg battle scenes work good.
The big day:
First, make sure you have done a fair share of drill with all the horses so they are not fresh out of the pasture and are used to being close with the others as well as interested in resting calmly.
Use a snaffle bit on your horse and take your spurs off. Too many people have inadvertently spurred their horse or jerked on his mouth if he reacts to gunfire. In effect, this tells your horse the big noise and smoke DOES hurt! You want him to have a good experience. Have him stand next to some old campaigners who could care less about gunfire. He will learn a lot from their attitude. Control your own fears and nerves - whistle or sing a song while this is going on, its hard to hold your breath (a sure sign of nerves) when you sing.
When training like this I usually ride my good gun horse 200 feet away and fire off him with the line of horses being trained watching so they can see his lack of fear. Usually if everyone did their homework we have no incidences of fractious horses. If a horse is skittish enough to leave the line, the rider should not fight him, allowing him to react and then guiding him back into the line from the rear. I don't advocate petting and reassuring physically at this point, I want the horses attention on the action and what the other horses are doing.
I move in closer to the others and fire again several times. We try several different things at this point if things are moving right along. I might ride on one end and then the other of a battle line and fire or might form a column of twos or fours and ride around it firing while they walk along. When its time for each horse to have his rider fire off his back he rides next to my gun horse while I fire alongside him without the security of the other horses. When he is good with that I hand the rider a pistol and continue to ride alongside while he fires. Upon completion of this phase we add more speed to the action when all are calm and obedient. Speed excites horses so if they are unable to handle gunfire at a walk they must not graduate up to a trot or gallop until they are ready.
This method works fine with all horses. I have never seen it fail. Some horses are skittish longer than others and require more work but overall, if the horse is not traumatized by bullying behavior on the part of the rider he will develop into a calm troop horse in no time.
We take our horses-in-training to reenactments and keep them on the picketline so they can get used to the sounds of battle from there, they move up to drill on the outskirts of the battlefield and then to actual combat when they are ready.
If you are unable to train your horse to withstand gunfire I would suggest that you look for another horse rather than put yourself and others at risk on the battlefield.
Article written by Linneus Ahearn