He was born on November 3, 1805 at St. Louis, Missouri, United States, of French parentage, the second son of Gregoire Berald and Palagie (L'Abadie) Sarpy. His father was a merchant and fur trader.
His father died in 1824, and his elder brother, John B. Sarpy, was employed in the firm of Berthold & Chouteau, the promoters of the Missouri Fur Company, and later associated with the American Fur Company.
Peter was favored with the best educational opportunities in St. Louis.
At an early age, probably 1823, Peter was employed as clerk of John Pierre Cabanné, the agent for the Missouri and American Fur companies at Council Bluffs. He was put in charge of the post established at Bellevue on the west bank of the Mississippi. For Cabanné he executed the arrest of the Leclerc party, 1832, and this is one explanation of his military title.
He was unusually successful in dealing with the Indians. As a licensed fur trader at the fork of the Missouri and Platte rivers he commanded a post of strategic importance. Situated on the edge of the Indian reservation he carried on a large business with both the natives and the whites.
In 1842, Sarpy was employed to build a ship. Brigham Young on his first expedition sought the trader's assistance, and the latter, after offering supplies and ferrying the party over the river, negotiated with the Indians for a friendly passage and escorted the Mormon leader beyond the point of greatest danger. Sarpy had a significant part in the negotiation of the land session treaties with the Omaha and Oto Indians in 1854.
The next year two regiments of Nebraska volunteers were raised for defense against the Indians, and he was made quarter-master of the brigade. To carry the immigrants and travelers he established ferries over the Missouri, the Elkhorn, and Loup rivers. He introduced a steam ferry service between St. Mary, Iowa, and Bellevue, Nebr. He also established a post store at St. Mary chiefly for supplying the white travelers and settlers, and he founded the St. Mary Gazette.
In 1862 he removed to Plattsmouth, Nebr. , where he lived until his death.
He was the owner and operator of several fur trading posts, essential to the development of the Nebraska Territory. Besides, he helped lay out the towns of Bellevue and Decatur, Nebraska. Nebraska's legislature named Sarpy County after him in honor of his service to the state. Sarpy expanded his ferry business in two locations: to cross the Elkhorn River at Elkhorn City, and at a fork of the Loup River near present-day Columbus. By the 1850s, his fleet included a steam ferry.
He was a colorful leader, short of stature with a handsome face and piercing dark eyes, a man of prompt action, unfailing courage, and vivid emotions.
Nicomi, his Indian wife, the daughter of an Iowa chief, was his strong ally, but her generosity cost him large quantities of supplies. He left no descendants, and his estate, except an annuity for Nicomi during her lifetime, went to relatives in St. Louis.
