In answer to Cannonballguys question: "In closing, I've got two questions for Creskol:
1- As the drawing posted by BosnMate shows, the wagonhorse harness-with-traces seems to be for use by a single horse. Was it also used for two horses side-by-side?
2- Was the harness-with-traces ever used for a team of more than two horses? If not, that would exclude it from being Artillery horseharness, because you needed no fewer than four horses to pull the enormous weight of a cannon or a caisson (artillery ammo-wagon)."
Yes, each animal in the team has exactly the same harness with the same traces. The wheel animals, "wheelers," have
a tongue between them. If the gun is being pulled by a "four up" the front animals are the leaders, however if they are
using 6 horses or mules, the front team is the leaders, and the middle animals are called the "swing" team, then the
wheelers with the tongue between them. The 4 up leaders have a chain that attaches to the tongue on the caisson at one end and
the lead teams double tree on the other. I found a pretty good picture that will explain better than me trying to type all this
information.
View attachment 859257

This is a 20 mule team, note each animal has the same harness. In this photo, the traces have much
longer chains, I think this must be what Cresol was talking about. There is short leather trace coming from the collar, then
a long chain. Anyhow, the picture shows the leaders and shows how the traces are attached to a double tree. From that
double tree, there is a chain running all the way to the wagon tongue, and each team except the wheelers are attached to,
and have that chain running between them. The leaders don't have the chain between them, the chain ends at their double
tree. This is a side note. Before I was a kid, the farmers in Shandon, Calif. freighted their grain using large wagons and trailers
pulled with 20 mules. By the time I was old enough to realize what was going on, there was only one 20 mule team left, and the
town of Paso Robles had a pioneer day parade every year, and the last 20 mule team pulled wagons in that parade. Grandpa
required that we watch the parade at a sharp corner that those mules and the wagon had to get around. At that corner, the leaders
(several lead teams) would make the turn, and if I remember correctly, three teams in front of the wheel animals jumped the chain
and pulled the wagon straight until it got to the point it could make the turn. Then they jumped back over the chain and made the
corner. Then those mules started dying off, and by the time I was 10 or 11 the team was no longer in the parade. I would
have never known the mules jumped the chain, except Grandpa made sure we saw it. Back to your artillery question. Each animal
on each team wears the same harness with the same type of traces that are attached to double trees. The wheelers have a tongue
between them, the swing has a chain between them, and the leaders have nothing between them. Note in the photo. A stick can be
seen between the two lead mules, attached from the bottom of the one's collar and the head stall of the other. That's called a "spreader"
where I come from, and keeps each animal from having a mind of it's own, keeps them both going the same direction. The 20 mule
team was controlled with a "jerk line." I have no idea how that works, except that each mule had a name, usually preceded with an
adjective not used in gentile society, and he had a pocket of rocks. A stage coach the driver used lines to control each individual animal,
so he has leather straps or lines between all his fingers, and he's using both hands. Just as a side note, reins are not use with harness animals,
at least where I come from on either driving or work teams or even individual driven animals, reins are called "lines." However artillery was
different, in that the horses were ridden instead of driven. Here is a picture of some reenactors pulling a gun with a 6 up.
View attachment 859285

This picture doesn't have anyone riding on the caisson, which would have been done in the Civil War.

This lithograph shows a couple of guys riding the caisson.

This is a great photo of what looks like WWI era field artillery. Note the guys on the caisson, and the empty
saddle on the closest horse. Which shows me that artillery harness wasn't exactly like other work harness but they had traces and
double trees, the difference would be the saddles.
Another side note, when I was in college, a couple of the guys that I rodeo'd with were from the LA area, and had part time extra
jobs in the movies. One of those guys had been an extra in a movie that the name is long ago forgotten. He was on a gun crew
in the movie, and was riding a wheel horse. The scene required the horses to run, and skid the gun around a corner. He said the
tongue like to tore his leg off. He had to wear a shin guard plus wrap a blanket around his leg.
Every body that has read this, please, this information is from limited memory a long time ago, I've done no
study on the subject. My words are mine and the old timers I learned from, they aren't necessarily the facts,
so don't write your doctorate thesis on what I say. If you disagree with me, I don't care, it's my memories with
all the flaws of old age, and it's darn sure too late to change now.