Pierre A. Gentieu (1842-1930) was a photographer and a long-term employee of E.I. du Pont de Nemours & Company, a chemical company more commonly referred to as the DuPont company. Gentieu was born in France in 1842. He immigrated to the United States in 1860. As a member of the local militia in New Orleans, Gentieu refused to swear allegiance to the Confederacy. In July of 1862 he enlisted with the 13th Regiment of Volunteers of Connecticut, which was formed in Louisiana.

He began working for DuPont in 1877 and remained a loyal employee until his retirement in 1911. In 1879, while on a lunch break, Gentieu painted the Lower Yard. The painting impressed his direct supervisor, Lammot du Pont (1831-1884), who requested that Gentieu photograph it so that various members of the du Pont family could have a copy. Shortly thereafter, Gentieu was promoted to making sieves for separating powder grains. In 1881, he was promoted to yard clerk, and then later store keeper at the mills.

Drawing and photography were among Gentieu’s favorite pastimes. The du Ponts allowed Gentieu to photograph the DuPont Co. plant, property, family members, and their homes. He created an invaluable photographic record of the company's Brandywine Mills at the turn of the twentieth century.