The German military constructed several fortifications in the area around Frederikshavn. The most recent occurred during World War II, when the Germans enveloped the town in concrete. However, the Germans had already been in the area in the early 1600s when Christian IV, with very little success, involved himself in the Thirty Years' War.
One result of the Danish king's involvement was that Jutland was left open to the ravaging troops of Wallenstein. These troops reached as far as Vendsyssel, including Fladstrand, where Lieutenant Colonel von Hatzfeldt built a redoubt to protect the Germans against a landing by the Danish fleet.
The redoubt still exists today and is now called Nordre Skanse. Today, there is a small dinghy harbor, Skansehavn, which local residents can use. Additionally, cannons are on display at the redoubt
