Fort Union, one of the largest and best known trading posts in the American West, was located on the Missouri near the mouth of the Yellowstone, about 14 miles southeast of here. Built in 1828, it was the headquarters for the American Fur Company's newly created Upper Missouri Outfit. From the fort, the company ruthlessly crushed its opposition while conducting a profitable trade with the Assiniboine, Gros Ventres, Mandan, and Blackfeet Indians. Fort Union was a substantial post with stone blockhouses on opposite corners of the stockade, which enclosed the manager's opulent residence, a barracks, warehouses, a powder magazine, and stables. Guests to the remote outpost were comfortably housed, well-fed, and lavishly entertained by the company's manager. There was also, however, a dark side to the post. Its history was "a continuous series of conspiracies, family feuds, sieges, pitched battles, drunken brawls, and cold blooded murders." By 1840, the price of furs and hides fell and Fort Union began a long decline. In 1865, the U.S. Army took over the post. Two years later the army dismantled the buildings and moved them across the Missouri to construct Fort Buford.