Napoleon wanted to fortify the place, and transfer the Amsterdam navy base to Den Helder.

[4] Indeed, King Louis regularly talked about the subject with Cornelis Krayenhoff, then director of fortifications in the department where Den Helder was located.

[5] Kraijenhoff came with a plan to build: A fort at the Kijkduin dune, this would cover the Schulpengat, and allow mortars to cover the approaches to Nieuwediep; A brick fortress tower, tour-modèle behind the Kaaphoofd battery; another such tower at the southern end of Den Helder village; one more tower on the Sluisdijk; changing the Nieuwe Werk to a fortress; Building a fortress on top of the shoal De Laan.

Den Helder and the base would be protected by a string of fortifications, costing 6 million Francs.

Somewhat later, the construction of Fort Dirksz Admiraal began, and het Nieuwe Werk was changed to a fortress.

[7] During the revolt which led to the establishment of the Sovereign Principality of the United Netherlands, the naval base of Den Helder was held by the French side.

[8] Though not much was done in terms of besieging Den Helder, the siege lasted till 21 April 1814.

[9] In February 1818, a commission was appointed to investigate the defense of Den Helder and the Naval base Willemsoord.

Most of these should be able to penetrate armor at a distance of 2,000 m.[15] In 1870 the fortress law asked for money for a fort on the Zuidwal.

While the Dutch navy first standardized on the 9-inch Armstrong muzzle loader, the army looked to France and Germany.

In 1870 the Dutch army got the 24 cm ijzer, an iron rifled breech loader based on a French model.

[17] In 1879 Minister of War Den Beer Poortugael took the lead and secured money to build Fort Harssens.

During World War I the Fortifications of Den Helder were manned by the mobilized Dutch army.

Just before World War II the fortifications and their guns no longer posed a serious threat to enemy warships.

During World War II, the German army garrisoned the Fortifications of Den Helder.

For Germany the base was important for the small craft of its navy and to protect coastal shipping.

Post World War II, fortifications like those of Den Helder were completely obsolete.

The first activities were guided tours at Fort Kijkduin, which also aimed to raise public awareness of the fortress.

[23] The end of the Cold War would lead to less work for the Dutch military, which the municipality tried to compensate by developing tourism.