When Mexico gained independence from Spain in 1821, the Santa Fe Trail was the trade route used to supply Mexico with manufactured goods produced in the U.S. Goods were shipped, sold, and traded in Santa Fe, Mexico. At first there were no military escorts for the wagon trains transporting goods. They were at risk of hostile Native American attacks, a threat that became so apparent that travelers and traders began petitioning the U.S. government to provide military escorts for protection. Fort Leavenworth was established in 1827 to provide this much needed protection on the Santa Fe Trail. In 1829, Major Bennet C. Riley, stationed at Fort Leavenworth, along with three companies of the 6th Infantry and one company of riflemen served as the first protective services on the trail. Major Riley later reported that the Infantry was not mobile enough to provide adequate safety for the wagon trains. He believed a mounted force would be more effective. After the need for a mounted force became more apparent, the U.S. Congress authorized the Regiment of Dragoons in 1833. The Dragoons became the first horse-soldier force for the U.S. since the War of 1812 and served In that capacity until the 1860s when they were converted into the Cavalry.
Army wagons became a common sight on the Santa Fe Trail. In addition to providing protection, Army wagon trains were needed as expeditions out west increased. During the 1830s and 1840s the Army conducted many missions for the purpose of exploration and reconnaissance. Many expeditions used the Santa Fe Trail as an outward bound route and for a return route. The Army preferred to use mules to pull their wagons, usually in teams of four, because they could pull heavy loads at a fast speed. Army wagons were usually painted Venetian red and blue per Army regulation. The Army hired civilian teamsters to drive the wagon trains. In addition to driving the wagons, teamsters were responsible for packing the wagons, wagon maintenance, and taking care of the mules. The Army preferred civilians as teamsters rather than soldiers because civilians were less likely to desert their position. Many civilian teamsters already had experience with driving wagon trains due to the increase of freighting during the 1840s.
See a depiction below of what an Army wagon train looked like accompanied by a teamster and dragoon, on display at the Frontier Army Museum.