Dey Mansion

The story of Dey Mansion begins with that of Dirck Janszen Siecken Dey. A soldier with the Dutch West India Company, he settled in the Dutch colony of New Amsterdam (now New York) in 1641. More than four decades later, his grandson, who also had the first name Dirck, purchased 600 acres of land in the Preakness Valley, in what is now Wayne Township, Passaic County, New Jersey. In 1764, the property came into the possession of his son, Theunis Dey, who at the time was a thirty-eight-year-old husband and father of nine. 

It is unclear exactly when the mansion was constructed and by whom. Some sources suggest that Dirck Dey built the home on the property in the 1740s and then willed it to his son. Other sources hint that Theunis Dey, after inheriting the land from his father, built the mansion around 1770. Regardless of exactly when it was constructed and by whom, Dey Mansion, with its symmetrical design, is a paragon of mid-eighteenth-century Georgian architecture. 

During the American Revolution, Theunis Dey was colonel of the Bergen County militia. His being elected to lead the local militia unit reflected his elevated social status in the community. A wealthy man, he served in the New Jersey Assembly in the 1760s and early 1770s. Dey also served a charter trustee of Queen’s College (now Rutgers University) and later represented Bergen County in the State Council.  

In July, October, and November of 1780, General George Washington used Dey Mansion as his headquarters. While Washington and his staff occupied a handful of rooms on the first and second floors of the house, the Continental Army camped outside on the grounds of the estate. During his time there, Washington penned 364 letters and orders and received over 600 communications, all of which are now housed at the Library of Congress in Washington, D.C. Washington and his army left Dey Mansion on November 27, 1780. 

After the war, the mansion passed out of the hands of the Dey family. General Richard Dey, Colonel Theunis Dey’s eldest son, sold the house and nearly all of the acreage in 1801. Throughout the nineteenth and early twentieth centuries, the mansion passed through various owners and remained a private residence. In 1930, the Passaic County Park Commission purchased the home and some of the surrounding acreage. A few years later, the mansion underwent a complete restoration. Directing the restoration efforts was Charles Over Cornelius, an architect and former curator of decorative arts at the Metropolitan Museum of Art in New York City. In the fall of 1934, Dey Mansion opened to the public as a historic house museum. In 1970, it was listed on the New Jersey and National Register of Historic Places. More recently, in 2016, it underwent another full-scale renovation. Today, Dey Mansion continues to operate as a historic house museum, owned by the County of Passaic and operated by the Department of Cultural and Historic Affairs. Visitors can take hour-long guided tours of the home, participate in hands-on workshops, and view live historical demonstrations. 

"History." Dey Mansion Washington's Headquarters, 1780. County of Passaic. Web. 28 September 2020 <https://www.deymansion.org/history>.

Labaw, George Warne. Preakness and the Preakness Reformed Church, Passaic County, New Jersey. New York: Board of Publication of the Reformed Church in America, 1902.