In order to shoot the scene where George Washington and his men cross the Delaware river, a major swath of the frozen Saranac River in New York had to be dynamited and then populated with 1400 extras in rowboats.
18th century Trenton, New Jersey, was recreated as an outdoor set, built in Plattsburgh, New York. The set included two streets, each 800 feet long, and forty-six houses.
According to author Richard Koszarski, this film used every available studio space in the New York area.
The sequence showing George Washington crossing the Delaware River utilized a reported fourteen hundred extras.