Fort de Cavagnal (1744-1760?) - Also known as Fort Cavagnolle, Post of the Missouri, and Fort de la Trinité, this was a French fort on the Missouri River, situated somewhere between Kansas City, Missouri and Fort Leavenworth, Kansas. Built in 1744, the fort was the furthest west on the Missouri River at the time and was first commanded by François Coulon de Villiers. The fort also doubled as a trading post operated by Joseph Deruisseau who had a monopoly on trade on the Missouri River from January 1, 1745 to May 20, 1750. It was described as: a small but substantial fort with a surrounding stockade of stout piles and with bastions at each of the four stockade corners. Internal buildings included a commandant's house, a guardhouse, a powder house, a trader's house, and a house for the trader's employees. The buildings were constructed of logs and most were covered with mud.

The exact location of the fort is not known because of conflicting reports about its relationship to trade with the Kanza tribe. British reports placed it below the confluence of the Kansas River and Missouri River in what is today Kansas City. However, most reports place it on the bluffs above the confluence of Salt Creek and the Missouri River just north of modern day Fort Leavenworth. This was a site of a major Kanza village, which Lewis and Clark visited on July 2, 1804. The fort was abandoned by France after Louisiana Territory was ceded to Spain in the treaties concluding the French and Indian War.