Fort Cavagnial (or Cavagnal) (1744-1764) – Not a military post, this fortress was one of many that was an early trappers and traders post. Established before the Louisiana Purchase, it was built by a French trader, Joseph Deruisseau, who, on August 8, 1744, was granted a monopoly to trade with the Indians along the Missouri and Kansas Rivers. The fort was named for Louisiana Governor Pierre François de Rigaud, Marquis de Vaudreuil-Cavagnal and was the most western fort on the Missouri River at the time.
The fortress was small but substantial, including log buildings covered with mud such as a commandant’s house, guardhouse, powder house, trader’s house, and a building to house employees. It was surrounded by a stockade and bastions at each corner. With plans to extend trade all the way to Santa Fe, New Mexico, the post thrived for several years until the advent of the French and Indian War, which seriously affected the Indian trade. However, the site continued to be utilized until the fort was abandoned by France after Louisiana Territory was ceded to Spain in the treaties concluding the French and Indian war.
The exact location of the post is not known, but, it was thought to have been on the bluffs above the confluence of Salt Creek and the Missouri River just north of modern-day Fort Leavenworth, Kansas. The fort was still standing when Lewis and Clark reported on the site in 1804.
By Kathy Weiser-Alexander, updated January 2018.