Working powder mills on Brandywine Creek, about 1905. Note the handwritten "These blow up occasionally, and then?"
|Location:||North of Wilmington on Delaware Route 141 at Brandywine Creek Bridge, near Wilmington, Delaware|
|Area:||191.2 acres (77.4 ha)|
|Architectural style:||No Style Listed|
|Added to NRHP:||November 13, 1966|
|Designated NHL:||November 13, 1966|
From 1802 to 1921, Eleutherian Mills was a gunpowder mill site used for the manufacture of explosives by the Du Pont family business. The name also refers to the house on the hill above the mills, which was the first Du Pont family home in America. The business was founded by Eleuthère Irénée du Pont. In 1952, the site became an outdoor museum and the Hagley Museum and Library was founded.
Jacob Broom built a cotton mill on the site in 1795. The mill burned down in 1797 and in 1802 he sold the site, complete with a working dam and millrace to Eleuthère Irénée du Pont, who paid $6,740 for the 95 acres (380,000 m2).
The first domestic supplies of high-quality gunpowder were made in the USA by E. I. du Pont de Nemours and Company. The company was founded in 1802 by E.I. du Pont, two years after he and his family left France to escape the French Revolution.
They set up the Eleutherian gunpowder mill on the Brandywine Creek just north of Wilmington, Delaware, based on gunpowder machinery bought from France and site plans for a gunpowder mill supplied by the French Government. They also built housing for 30 workers.
By the end of 1804, DuPont had sold 39,000 pounds of powder; the following year sales tripled. The Federal government and John Jacob Astor's American Fur Company became regular customers. In 1813 the Hagley property, just downstream from the original mills, was purchased, doubling the size and capacity of the mills. Sales grew during the Mexican-American War and the Crimean War. During the American Civil War, the firm sold 4,000,000 barrels of powder to the Federal government.
A major explosion killed 33 people in 1818. Another major explosion occurred on the site in 1847. In 1854 three gunpowder wagons exploded in the city of Wilmington.
The site 
The mill buildings used in the manufacture of gunpowder were built with strong stone-walled structures on three sides; but were only covered by light wood structures on the fourth side, which faced out onto the Brandywine Creek. When an accident occurred, the explosion was directed away from the other mills and storage areas and over the creek.
Water power was provided from a mill race behind the mills, thus further isolating the mills in case of accident. One water wheel was often used to provide power to two mills. Water turbines were introduced in the 1840s. Alfred Victor du Pont acquired additional property, down stream from the Eleutherian Mills, to add to the manufacturing site. One of these properties was called Hagley, and it became known as the Hagley Yard.
Most of the industrial remains are located in the Hagley Yard. The mills were used in the purification, crushing, and mixing of charcoal, sulfur, and saltpeter. Other mills in the complex were used for glazing and corning, making metal powder kegs, and in cotton and woolen manufacturing. Stables, offices, a machine shop, and a steam powerhouse from the late 19th century also were located in the complex, as was a narrow gauge railway.
Rundown and closure 
See also 
- Ballincollig Royal Gunpowder Mills
- Faversham explosives industry
- Waltham Abbey Royal Gunpowder Mills
- "National Register Information System". National Register of Historic Places. National Park Service. 2010-07-09.
- "Eleutherian Mills". National Historic Landmark summary listing. National Park Service. Retrieved 2007-09-27.
- Richard Greenwood (1979) National Register of Historic Places Inventory-Nomination: Eleutherian Mills, National Park Service and Accompanying 12 photos, from 1966-1975
- Kinnane, Adrian (2002). DuPont: From the Banks of the Brandywine to Miracles of Science. Wilmington: E.I. du Pont de Nemours and Company. ISBN 0-8018-7059-3
- Brown, G.I. (1998). The Big Bang: A history of explosives. Thrupp: Sutton Publishing Limited. ISBN 0-7509-2361-X.
- du Pont, B.G. (1920). E.I. du Pont de Nemours and Company: A History 1802 to 1902. Boston: Houghton Mifflin. ISBN 1-4179-1685-0
- DuPont Powder Mill, Hagley Museum, on Brandywine River, Greenville vicinity, New Castle County, DE: 3 photos, 4 drawings, 3 data pages and supplemental material, at Historic American Building Survey
- The DuPont Company on the Brandywine (A digital exhibit produced by the Hagley Library that covers the early history of Eleutherian Mills]