John Benjamin O’Fallon was born on 17 November 1791 in Louisville, Jefferson County, Kentucky. He died on 17 December 1865 at the age of seventy-four in St. Louis. O’Fallon, Illinois, and O’Fallon, Missouri, are named after him.

John received his education in law at an academy (which later became Centre College) in Danville, Kentucky, financed by his uncle, William Clark. In 1810, John went to Lexington, Kentucky, to further his education. While there, he studied law under Robert Todd, whose daughter would later marry Abraham Lincoln.

John joined the army in 1811 and was severely wounded at the Battle of Tippecanoe. He was promoted to ensign in the First U.S. Infantry in September 1812 and served throughout the War of 1812 under Gen. Benjamin Harrison, who became a close personal friend. John was based in St. Louis by 1813 where, assisted by his uncle, Gen. William Clark, he worked for the Missouri Fur Company

John was promoted to first lieutenant in the 24th U.S. Infantry and in August 1818 he was again promoted to the rank of captain in the 2nd U.S. Rifle Regiment. He resigned his commission in the army later that year. John acquired the “colonel” designation when he was appointed the first adjutant general of the Missouri State Militia in 1820. In 1821, John was an elected a member of Missouri’s first state legislature. He was the first president of the St. Louis branch of the Bank of the United States, and in 1857, Col. O’Fallon donated more than $1,000,000 to establish the O’Fallon Institute at what is now Washington University in St. Louis.

Later John was a contractor, buying and selling supplies to the army. This proved a profitable business, and he accumulated a considerable fortune. He invested his newly acquired wealth in very lucrative enterprises, among them several railroads. In 1860, the value of John’s real estate was $1,5000.000 and his personal estate was valued at $500,000.

His most gainful investment was in two large tracts of land now part of northern St. Louis, which he subdivided into building lots. On one part of these tracts, he built a large country home, which he named Athlone for the town in Ireland from which his father had come. This 160-acre estate was later acquired by the city of St. Louis in 1875 and is now O’Fallon Park. Among his other accomplishments, he donated the land on which St. Louis University stands.

John and Harriett Stokes were married in St. Louis on 15 April 1820. Harriett was born about 1801 in England. After giving birth to four children, none of whom lived to maturity, Harriet died in St. Louis on 14 February 1827 at the age of twenty-six.

John and Ruth Caroline Sheets were married on 15 March 1827 in St. Louis. Caroline was born on 22 November 1804 in Baltimore, Maryland, and died in St. Louis on 24 September 1898 at the age of ninety-three.

John made his lengthy handwritten will on 5 June 1865, itemizing his bequests to his wife, children, grandchildren, brothers, sisters, and friends. It was approved for probate on 23 December 1865.

John O’Fallon and Ruth Caroline Sheets had the following children, all born in St. Louis: Caroline Mastin, James Julius, Benjamin, Henry Algernon, and John Julius O’Fallon.

Written by Ted Steele
February 2021
© 2021, St. Louis Genealogical Society

Return to St. Louis City/County Biographies.

Last Modified: 29-Jun-2021 17:27