The Premise is Unbelievable.

The premise is unbelievable for many reasons.

Location of Jackson's ranch/Pierce's gold mine near the fictional town of Emmett.

Taw Jackson said about the war wagon: "It takes an average shipment of fifty thousand in gold from Emmett to the railhead in El Paso 43 1/2 miles away."

So it could be in the states of Chihuahua, Mexico, or Texas, USA, or New Mexico, USA, and with an English name probably not in Mexico.

As near as I can tell the nearest gold mines to El Paso are over a hundred miles away in Texas and about a hundred miles away in New Mexico.

Daw Jackson calls El Paso the railhead, not the railroad station.

He could mean either the first definition of railhead, "The farthest point to which the rails of railroad have been laid." or the third: "A railroad depot at which supplies are unloaded to be distributed or forwarded by truck or other means."

The Southern Pacific Railroad crossed southwestern New Mexico and reached El Paso, Texas from California May 19, 1881, and linked with the Texas and Pacific Railroad in Texas 7 months later on 15 December, 1881. The Atchison, Topeka, and Santa Fe railroad coming from the north reached Las Cruces, New Mexico in 1881 and El Paso soon after.

So El Paso was the railhead by the first definition for 7 months in 1881, and the railhead by the third definition anytime since May 19, 1881. The Fictional town of Emmett should be in south central New Mexico, northeast of El Paso, and away from stations on the railroads north, west, and southeast of El Paso.

The AFI Catalog of Feature Films says that the date is the 1870s and that Kiowa Indians participate in the attack on the war wagon. So maybe the War Wagon is in a fictional alternate universe where some railroad reached El Paso in the 1870s, and where the Kiowas were not on the reservation as early as in real history.

The War Wagon has the following dialog:

Levi Walking Bear: Dumb Indians!
Taw Jackson: Looks like they're getting ready to move out.
Levi Walking Bear: They are. Squaws, old men, children - Pierce has starved them out. He'll have all the land now.
Taw Jackson: What about Wild Horse?
Levi Walking Bear: He and the warriors are stayin', but Pierce will hunt them down, too. Dumb Indians.

And that doesn't make sense. The Kiowas were nomadic hunters and warriors, and wouldn't stay in a small area outside of their normal hunting grounds for long enough for Pierce to evict them. The last holdout Kiowa bands surrendered and went to the reservation in Oklahoma during the Red River War of 1874 to 1875. And the southern buffalo herd shrank and disappeared during the period of 1870 to 1876, leaving Kiowas with no means of support if they left the reservation.

The Kiowas had no legal claim to any land 43.5 miles from El Paso, so if there was a Kiowa band with 100 fierce warriors hanging around, Pierce wouldn't want to risk angering them by stealing any land around Emmett from them - since they didn't own any land around Emmett to steal. Instead he should logically have hired the 100 fierce Kiowa warriors to serve as additional guards for his mines and war wagon.

And why would Pierce want to hunt down the 100 Kiowa warriors? Indian wars were very expensive, so why would a businessman want to waste his money paying for an Indian war instead of getting the army and/or the Indian Bureau to take the Kiowas away for free?

Did the Vanderbilts ever volunteer to pay for an Indian war? No. And they were a lot richer than Pierce was with his measly $ 50,000 gold shipments.

And why was the gold in the form of gold dust? Was the gold found in some ores that had to be ground up to free the gold, thus turning the gold into dust?

Anyway, despite the fact that it would have been comparatively easy to find a situation where the story made sense, the story of the War Wagon could not have happened in the real west.