Answer: The Texas Rangers
The gunfighter left on horseback, with his Indian friend Sam Sharpnose on horseback, and a mule carrying the ransom. The Texas Rangers attempted to assist while using the new horseless carriages. They were planning to ambush the kidnappers and take off as fast as they could. When they got to the ambush site, they themselves were ambushed and took heavy losses. The Duke's character and Sam came plodding along on horseback. Two of the gunfighter's sons were riding with the Rangers and, unhurt, choose to ride with their father in spite of the strained relationship. The Rangers were left on the side of the path to await assistance.