Eleven concrete sentinels silently keep watch as Delaware beach- goers bathe in the sun and splash in the surf, many unaware of the history of the towering cylinders.

The “fire control towers” that dot most of the Delaware coast went up 75 years ago as part of a defense against German U-boats and other warships during World War II.

The observatories worked in tandem, allowing soldiers peering through the horizontal slits cut into the towers to triangulate the dis- tance of enemy ships. They would then radio the coordinates back to the massive guns at Fort Miles located at Cape Henlopen.

The U.S. Army commissioned the construction of 15 towers be- tween 1939-1942 in Delaware and New Jersey. According to the Dela- ware Division of Historical and Cultural Affairs, the towers range in height from 40 to 90 feet, have a diameter of 17 feet and have 1-foot- thick walls.

The towers were built with an expected lifespan of a decade or two, but most have stood for generations.

The 11 Delaware towers are located between Fenwick Island State Park and Cape Henlopen State Park. Two of the four built in New Jer- sey remain. One of those, Fire Control Tower 23, is at Cape May Point State Park and has been restored and is open to the public. The other remaining tower is inside the Grand Hotel in Cape May. Two others were torn down.

The historic structures are constantly under attack by nature. Blowing sand, coastal erosion, storms and rising tides are all threats. The original metal staircases in most of the towers have rusted and windows have blown out. All but one in Delaware is sealed shut and closed to visitors. Fire Tower 7 in Cape Henlopen State Park was re- stored and is open to the public. At 75-feet, it offers a panoramic view of Lewes, the Delaware Bay looking toward Cape May, the Atlantic Ocean and Rehoboth Beach to the south.

One of the Delaware towers in the park was converted in 1986 to a radar tower used to monitor incoming and outgoing traffic into the Delaware River.