William Henry Ashley and Andrew Henry raise Ashley's Hundred and leave St. Louis

Recruitment. Ashley and Henry published advertisements in St. Louis newspapers seeking 'One Hundred enterprising young men' to ascend the Missouri River for employment lasting one to three years. These recruits, later called 'Ashley's Hundred,' included notable figures such as Jedediah Smith and Jim Bridger. The caliber of men sought established the prototype for the 'mountain man' archetype.

Operations. The company initially worked lands around the upper Missouri River, facing competition from the Missouri Fur Company, which had already built outposts along the river. In its later operations the firm pioneered a brigade-rendezvous system, formed in part as a reaction to a July 1822 law prohibiting the sale of alcohol to Native Americans. Major Henry trained Euro-Americans and Métis to trap independently and meet at temporary trade gatherings, adapting methods of the Northwest Company and Hudson's Bay Company to the central Rockies.