Larpenteur was the son of a Bonapartiste gentleman who left France in disgust after the Bourbon restoration, and settled in Baltimore with his family.

The outfit under Robert Campbell first moved overland, with pack train and cattle, to the Green River rendezvous.

The outfit went west over St. Paul and Pembina, and Larpenteur erected a trading post at Poplar River.

In 1866 he served as an Assiniboine interpreter for the Indian Peace Commission, and the following year he became a fur trader for Durfee & Peck, but was fired after a conflict.

[9] During his forty years in the fur trade Larpenteur diligently kept a diary, using it as a source to complement his memory when he wrote his memoir.

Unable to finance publication of the memoir, he sent the manuscript to Washington Matthews, a U.S. Army surgeon he had known at Fort Buford.