Fort Delaware as it lies. Thanks to the Endicott Board, which determined that the US would be unable to defend its shores from an attack by a flock determined geese (much less the wholly imagined Spanish Armada) at the end of the 19th century, Fort Mott on the New Jersey side of the Delaware and Fort DuPont on the Delaware side were built in an effort to make any force trying to steam up the Delaware on its way to Philadelphia...blow up.