George Washington used the Dey mansion as his headquarters during the Revolutionary War.James LaForge/Business InsiderThe Dey Mansion is an estate in Wayne, New Jersey, about 20 miles from New York City.For three months in 1780, George Washington and his officers headquartered at the mansion.The home has passed through nearly 20 owners, but some original artifacts from the time remain.When Americans picture the Revolutionary War, they might conj…