The staff at Dey Mansion is committed to conserving and presenting the history of the Dey Family and the significant role that their property played as General George Washington’s Headquarters during the summer and autumn of 1780, under the auspices of the Passaic County Board of County Commissioners. The Dey Mansion encourages research into Colonial American life, the American Revolution’s events and participants, as well as the need and value of historic preservation via tours, lectures, and special events.
The County of Passaic owns the Dey Mansion, managed by the Department of Cultural & Historic Affairs.
Theunis and Hester Dey lived at the Dey Mansion, which was erected in 1770 and served as General George Washington’s headquarters in July, October, and November of 1780. One of the Dutch West India Company’s soldiers was named Dirck Janszen Siecken. Dey landed in New Amsterdam in 1641, establishing the Dey family’s origins in the American colony (New York). After the English took control of the majority of New Amsterdam in 1674, Dirck Siecken was listed among the colony’s finest and wealthiest citizens. More than forty years later, his grandson Dirck, who was also called Dirck, acquired six hundred acres in Preakness, now Wayne Township, New Jersey, from Thomas Hart’s heirs. When Theunis Dey inherited the estate in 1764, he was thirty-eight (38) years old, married, and the father of nine children. He assumed a significant position in the public sphere, serving as the State Council representative for Bergen County and a founding trustee of Queen’s College (now Rutgers, the State University).
As Washington’s Headquarters
One of General Washington’s military field headquarters, the Dey Mansion, is still extant today. Theunis Dey was the colonel of the Bergen County Militia during the American Revolution, which put him in close contact with Washington.
The friendship between Dey and Washington was described by historian Isaac A. Serven as follows: “Besides shared principles of liberty and
They had interests other than only military secrets. Both individuals had similar ages, were significant landowners and farmers, and held civil office in their respective countries’ county and state governments.
In a military setting, Washington’s army camped in the “vicinity of the Passaic Falls” due to its advantageous location and easy access to food and forage. The residence, known as “Bloomsbury” by Colonel Dey, was used by General Washington from Saturday, July 1, to Saturday, July 29, 1780. From Sunday, October 8, until Monday, November 27, 1780, the top executive once again made the house his base of operations.
The sole military action that Washington ordered in July was Brigadier General Anthony Wayne’s assault on Bull’s Ferry. Washington learned of the French allies’ arrival in Newport, Rhode Island, on July 14. On July 29, 1780, the main commander departed after making arrangements to meet with them.
Washington campaigned in the Hudson Highlands, had talks with the French, and dealt with “treason of the blackest color” inside his own forces between July 29 and his return on October 8, 1780.
Major-General Benedict Arnold’s treacherous actions were made public at the end of September. Major John André, Arnold’s accomplice, was executed on October 2 at Tappan, New York. Sir Henry Clinton, the British commander, desired to seize Washington in order to exact revenge for André’s murder. The supreme commander made the decision to relocate his troops to the more difficult-to-reach Preakness Valley.
Two military operations took place during the encampment in October and November. Major General Lafayette conducted an unsuccessful assault on Staten Island. As part of the second maneuver, reconnaissance groups led by Lafayette, Moylan, and Humphrey moved closer to Fort Lee in preparation for an assault on Fort Washington. The operation was halted by the top commander. A portion of Washington’s army went to Morristown on November 27, 1780, and a few regiments from Pennsylvania and New Jersey were cantoned in Pompton as he departed the Dey Mansion.
Documents confirming the importance of the Dey Mansion as a military headquarters may be found among the Washington archives at the Library of Congress. General Washington sent 364 letters and directives for and on behalf of the Continental Congress to army commanders at the residence, totaling 594 pages. Washington received 610 correspondence totaling 1,275 pages while residing at the estate.
Dey Mansion Afterwards
In 1801, Colonel Dey’s oldest son, General Richard Dey, sold the homestead and 335 acres of property. From that point on, the home and its surrounding land were owned by several private owners until January 10, 1930, when the Passaic County Park Commission bought it. Charles Over Cornelius, an architect and former assistant curator of ornamental arts at the Metropolitan Museum of Art, oversaw the restoration during the winter of 1933–1934. On October 8, 1934, the Dey Mansion was made available to the public.
General Richard Dey, the eldest child of Colonel Dey, sold the house and 335 acres of land in 1801. The house and the surrounding grounds changed hands multiple times over the following years until they were acquired by the Passaic County Park Commission on January 10, 1930. The repair was overseen over the winter of 1933–1934 by architect and former assistant curator of the Metropolitan Museum of Art’s decorative arts, Charles Over Cornelius. The Dey Mansion opened to the public on October 8, 1934.
The Dey Mansion was added to the National and New Jersey Registers of Historic Places in 1970. The Passaic County Board of Chosen Freeholders started a significant initiative to further repair and renovate the Mansion in 2010. The Open Space, Farmland and Historic Preservation Trust Fund and the New Jersey Historic Trust provided funding for this project, respectively.
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