Forts Story and John Custis guarded the mouth of the Chesapeake Bay with 16-inch guns (M1919), the largest coastal artillery employed by the United States (the battleship USS New Jersey mounts 16-inch guns): They had a range of 25 miles.

Fort Monroe had several batteries that mounted 12-inch disappearing guns (M1895), with a range of 16 miles.

Fort Wool, which was built in the 1830's to provide further artillery coverage of Hampton Roads, mounted 6-inch rapid fire guns (Model I (T2)), which had a range of 14.7 miles.

This would have been the (approximate) level of artillery coverage at the start of the Second World War. Good luck getting in there, Kriegsmarine!