Fort Miles Fort Miles was an American military installation located on Cape Henlopen near Lewes , Delaware . Although funds to build the fort were approved in 1934 , it was 1941 before the fort was constructed . It was built to defend Delaware Bay and River and to protect domestic shipping from enemy fire within the capes , particularly from the German surface fleet . The fort was completed days before the attack on Pearl Harbor , Battery 118 ( Smith ) being declared operational on December 4 , 1941 . The United States declaration of war on Japan compelled the U . S . Army to man the fort with the 261st Coast Artillery Battalion , who days before were slated to leave . Fourteen vessels , including the USS " Jacob Jones " , a naval escort , were sunk off the coast of New Jersey during the first six months of 1942 . Numerous batteries ( ranging from 90mm guns up to 16 inch ) were installed at the fort and a large mine field was laid in the waters off Lewes , Delaware in the following years , but the fort was to see no action during the conflict . The soldiers would receive the surrender of " U - 858 " , a German U - boat that was part of Operation Seawolf at the time of the German surrender to Allied forces in Europe . At its peak , Fort Miles was home to over 2 , 200 soldiers , men and women , including the 261st Coast Artillery , the 21st Coast Artillery , the 52nd Coast Artillery ( Railway ) , the 198th Coast Artillery ( AA ) and the 113th Infantry ( det ) . Most of Fort Miles was declared surplus in 1948 and 1949 , but the Army continued to use portions of it through the early 1990s as a recreation area under the management of Fort Meade . In 1963 the US Navy took control of the southern end of Fort Miles including Batteries Smith and Herring to establish a SOSUS listening facility . " NAVFAC Lewes " would continue to operate as a top secret facility there until September 30 , 1981 . Fort Miles never saw any major action , only firing its guns once between its establishment and the end of the war . In 1964 , 543 acres ( 2 . 2 km² ) of federal land were donated to establish Cape Henlopen State Park . Over time , more land was transferred to the state park until Fort Miles ceased operation altogether in 1991 . Its last official usage was as a bivouac for soldiers that had just returned from the first Gulf War . Fire Control Towers , four to five story round - base concrete towers with flat observation decks , were set up as baselines to triangulate the position of suspicious ships or submarines . Five such towers still exist within the current boundaries of Cape Henlopen State Park , including one ( # 7 ) that has visitor access . Many bunkers were also constructed to house guns and other weapons . Barracks , administration buildings , and a pier were also constructed as part of the fort . The four largest coastal Batteries at Ft . Miles are Battery 118 ( Smith ) , Battery 221 ( Herring ) , Battery 222 ( Hunter ) , and Battery 519 . Smith originally housed the two 16 " guns , and is now in use by Cape Henlopen State Park for storage . Battery Herring , originally covered with sand like all the rest of the batteries , was excavated and expanded for use as a SOSUS station . It is now abandoned . Battery Hunter is in use currently as a Hawk Watch station . Battery 519 originally housed two 12 " guns . It is currently being renovated for use as a museum , celebrating Delaware ' s part in World War II . Tours began in 2004 . It has a restored 12 " cannon similar to the original mounted at the south gun block . Additionally , it is being used to house a German built 20 millimeter anti - aircraft cannon that had been captured from U - 858 after its surrender . Walking tours of the bunkers and other facilities currently being restored are available during summer weekends . The project falls under the pervue of the Delaware Department of Natural Resources and Environmental Control ( DNREC ) . Historic interpreters can be seen at the park during special events . These events are designed to give the public a demonstration of military life at Fort Miles when it was still in operation . Four Panama mount s still exist at Battery 22 , located near the Beach House within the park .