Colonel Sumner opened the first Fort Union in 1851, with the intention of serving as a protector for the Santa Fe Trail from the Apaches and the Utes Indians, and military supply for the entire southwest. The second fort was opened, in 1862, because of the poor living conditions of the first fort. The last fort, the third fort, was once the largest in the southwest.
The first Fort Union was established in July 1851, a few miles north of where the Santa Fe Trail split. Fort Union is located approximately eight miles northwest of present day Watrous, in the northeast section of New Mexico. Fort Union had been constructed by troop labor with little lumber, mainly poorly made adobe. The soldiers were too stubborn to ask the native people how to make adobe the correct way. Instead, they decided to take a shot in the dark, and make up their own recipe for adobe. Obviously, the fort walls, roofs and anything made of adobe quickly eroded. The conditions were so bad that the soldiers preferred to sleep on the ground outside, and risk being bitten by a rattlesnake, rather than sleep on their bed in their quarters. The fort was infested with deadly diseases such as small pox, measles, cholera, and dysentery, along with body lice. By 1860, something had to be done very soon and that is when the second Fort Union starts to be constructed. Today nothing remains of the first fort except the known location.
The second fort was moved a couple of miles east in relation to the first fort. It was intended to rid the soldiers of the diseases that plagued the first fort. Even the underground housing failed to keep diseases out of the living quarters. It was finished in 1862, and consisted of gun positions, underground infantry quarters, bunkers, storehouses, and a perimeter wall made out of dirt. The earth wall is built in a shape of a star for protection. Today, the remains of the earth wall are the only reminders of the second fort.