Dey Mansion The Dey Mansion , located in modern day Wayne , Passaic County , New Jersey , United States , and originally known as " Bloomsbury Manor , " played an integral role in the American Revolutionary War . Built by Dutch settlers in the middle of the 18th century it served as Washington ' s Headquarters on several occasions . Dey Family History . In 1641 Dirck Janszen Siecken Dey , a soldier for the Dutch West India Company , was the first of his family to settle in the colonies . His grandson Dirck Dey , a Dutch born planter , purchased 600 acres of land in Preakness Valley , now present day Wayne Township . The exact start date of construction on the Dey Mansion is unknown , but Dirck Dey started building it in the 1740s . By 1764 Dirck passed the mansion onto his son Theunis . Theunis along with his wife , Hester Schuyler , raised ten children in the mansion . Theunis was a political figure who served on the state council by representing Bergen County and was a member of the charter trustee at Queens college , now present day Rutgers University . He also served as a Colonel in the Bergen County Militia during the American Revolution . It was during his service in the militia that he came into contact with George Washington . This led to Theunis to offer his mansion to serve as Washington ' s headquarters . Washington ' s Preakness Valley Headquarters . George Washington utilized the Dey Mansion during the American Revolution as one of his many Headquarters . This area of the Preakness Valley ( in New Jersey ) was chosen specifically for its strategic location , as well as its abundance of food and forage in the surrounding area . On two separate occasions the Dey Mansion served as Headquarters for Washington , once from July 1 through July 28 , 1780 and again from October 8 through November 27 , 1780 . During his stay Washington and his advisers which included Alexander Hamilton , Robert H . Harrison , Tench Tilghman , David Humphreys and James McHenry used the four rooms on the eastern side of the mansion for their bedrooms as well as their military war rooms . Washington also had numerous visitors while at the Dey Mansion , those of which include the Marquis de Lafayette , General Anthony Wayne , Major General Lord Stirling , Benedict Arnold , General William Howe and the Marquis de Chastellux . Washington ' s letters and correspondences during his time at the Dey Mansion totaled 964 , for over 1800 written pages . One of which informed him on July 14 , 1780 that the French allied support had landed at Newport , Rhode Island . Washington left on July 28 to join them . During Washington ' s time away from the Dey Mansion Major , General Bendict Arnold ' s treason became evident and his accomplice Major John Andre was hanged in Tappan , New York on October 2 . Fearing that the British commander Sir Henry Clinton would seek revenge , Washington moved his army once again to the Preakness Valley ' s Dey Mansion , and arrived on October 8 , 1780 . He stayed there until November 27 , 1780 when he moved his headquarters and a portion of his army to Morristown , New Jersey . Layout of the mansion and surrounding property . The Dey Mansion is of Georgian style architecture with Dutch and English influences , and was built on a 600 acre lot in Preakness Valley , now present day Wayne , NJ . The Mansion was built facing the south in order receive sunlight . Each floor of the two story mansion features a long and wide center hall with multiple rooms on each side and an attic that spans the entire length of the mansion . The kitchen is located on an extension of the mansion which is separated by a stone floor hallway . Today most of the original wood frames and floors , along with some of the original furniture and art work still exist . It sits on a two acre plot of land , with features built onto the property including a blacksmith shop , plantation house and a courtyard in the middle of the three buildings . Dey Mansion through the years . Colonel Theunis Dey ' s oldest son General Richard Dey , sold the Mansion and 335 acres of surrounding land in 1801 . Since then sixteen different families have owned the mansion and land . List of Family Owners from its Construction to Present 1740 - 1801 Dey , 1801 - 1813 Neafie , 1813 - 1861 Hogencamp , 1861 - 1864 Yeoman , 1864 - 1865 Gillen , 1865 - 1866 Tainter , 1866 - 1875 Millington , 1875 - 1883 Howe , 1883 - 1889 Heeseman , 1889 - 1891 Islieb , 1891 - 1892 Heeseman , 1892 - 1901 Petry , 1901 - 1902 Heeseman , 1902 - 1906 Belcher , 1906 - 1907 French , 1907 - 1909 Murphy , 1909 - 1912 Wright , 1912 - 1918 Pfister , 1918 - 1930 Alsheimer , 1930 – Present Passaic County Parks On January 10 , 1930 the Passaic County Parks Commission acquired the land , and on October 8 , 1934 it was opened for visitors . Among the guests invited to its opening was President Franklin D . Roosevelt , and although he was unable to attend he wrote a letter in which he said , " You have made a real contribution to the history of the nation " ( See picture of letter ) . In 1970 the Dey Mansion was entered into the New Jersey Register of Historic Places as well as the National Register of Historic Places . As of 1987 the Dey Mansion has been open to the public as a Museum . It also acts as a meeting place and reenactment center for many historic groups such as the Hester - Schuyler - Colfax Chapter , Daughters of the American Revolution and the Sons of the American Revolution . The New Jesery Militia / Heard ' s Brigade also sponsors annual events at the Dey Mansion in February , October , and December .