Constructed between 1740-1750 by Dirck Dey, a Dutch-born planter, the mansion is an amalgam of Dutch and English influences, a rich and dramatic composition of country and urban elements that had few mid-18th century counterparts west of the Hudson River. Dey, in all probability, left the completion of the mansion to his son, Theunis. During the Revolution, Theunis commanded the Bergen County Militia. Colonel Dey offered the easterly side of the house to General Washington when the commander-in-chief used it for his headquarters in July, October and November of 1780.